Dwight,
You are exactly right in that as long as all the parts of the toggle assembly remain in the same plane, the toggle assembly will not unlock until the toggles bump the ramps on the frame. In fact it only takes the light initial pressure of the recoil spring to keep the toggle assembly in alignment. If the toggle knobs are allowed to raise only a fraction of an inch, which they can do without the breechblock moving, the toggle assembly is free to break at that point. The firing pin spring as well as the recoil spring work in conjunction with each other to keep the toggle assembly held in the proper plane at initial ignition. Also remember that the spring tension of the ejector riding on the breechblock also aids the breechblock in remaining in the proper position even if the two other springs are removed.

May this thread rest in peace -- but not without a post-mortem, as follows:

I believe <everyone> who posted here knew from the beginning that the Maxim/Borchardt/Luger toggle cannot remain locked against the primary recoil shock except by its geometry, that is by having the center pivot lowered just enough to want to break downward against the receiver (barrel extension) sides which block it solidly until the knobs are bumped upward against the ramps.

Many hundreds of words (all worthy and well-reasoned) were expended at cross purposes with Kyrie because the function of "holding the toggle closed" or "holding the breech block in battery" has two distinct meanings. Meaning No.1 is holding the toggle closed against small handling forces before firing, and meaning No.2 is holding the toggle closed against a huge rearward force just after firing. Both are design necessities.

Kyrie seemed to think that those people describing (correctly) how the recoil spring helps significantly in holding closed against small disturbances (No.1) were somehow denying or overlooking the fact that a depressed pivot is required to hold closed against main recoil (No.2). That's why there were so many go-rounds.

Kyrie was right in pointing out that a slowly lowered toggle, robbed of all kinetic energy, stalls and won't complete the cocking cycle with either flat or coiled recoil spring. But Johnny and others were right in pointing out that once the action <is> closed and cocked, the preload in the recoil spring is really the only significant force preventing the toggle from being jarred into breaking slightly the wrong way again before the user decides to fire the gun, resulting in a dangerous premature blowback.

One last thing. Many toggle mechanisms used in industry, such as clamps and locking pliers, hold themselves closed by jamming and deflecting a little as they go over center. The Luger toggle doesn't do that, as can be checked by removing the cannon (here we go again), taking out the firing pin spring and closing the breech on a spent shell casing. The breech block still has a little clearance, and the toggle knobs will easily move away from locked position that critical small amount unless an external force keeps them down.

I think long, redundant discussions of how the Luger was developed and how it works are at least as interesting as long, redundant discussions about the minutiae of collecting. So my thanks to Kyrie, who started it all, and everyone else who contributed.

One small point. When the toggles are slowly lowered to the in battery position and released a bit before arriving in battery, the action may or may not finish closing depending upon the particular pistol and recoil spring at hand. I have more than one of either example in my collection. The general trend in new model Lugers (with exceptions)is for the 9 mm to close and the 7.65 mm to remain open due to differences in the recoil spring.

DANG, youse guys really get into how things work!
Who wants to be the first to explain to me how in heck those Phasers that Worf and Picard use work? <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />

Faith Herb, they believe they work, so they do.

Man, am I glad that we got to a separate page. It got boring scrolling back and forth on this great discussion. I lost track more than once on the topic. I have a problem on an artillery that won't close the toggle and has a loading/unloading problem. The toggle closes to within about an eigth of an inch of full closure. At first I thought it was dirt a little notch in the barrels cone that the extractor fits in at closing. Now I am wondering if this is a problem with the mainspring? I am sorry that I am a bit OT but this is something that has been hanging me up for a long time.
Big Norm
<img src="graemlins/c.gif" border="0" alt="[ouch]" />

Norm, I agree that your problem does sound like a recoil spring or connector link problem. Do you have the same problem using different magazines? Tom H.

Norm, is it that your Artillery won't go into battery while working the action (i.e. you can close it with a push down on the toggle), or can you not actually close the breech?

I had the latter happen to me at the range one day (panicked me pretty good, I was shooting a matched byf41 which I intend to sell), I could not get the breech to close by about an eighth of an inch for love nor money, it was a hard blockage.

When I got home I stripped the gun down and discovered (to my great relief) that the striker spring pin at the back of the breechblock had rotated about an eighth of a turn, and that was what (somehow, I still don't know how, exactly) was blocking the last bit of breechblock travel. Rotated it back into position, worked perfectly.

Frankly I'm very sceptical of a spring problem here, I am in the camp which has it that the springs don't have very much to do with the initial opening or final closing forces on the Luger action. That being said, I hope my situation helps you out, good luck in tracking down your problem in any case.

--Dwight

[quote]Originally posted by Johnny Peppers:
<strong>Dwight,
The firing pin spring as well as the recoil spring work in conjunction with each other to keep the toggle assembly held in the proper plane at initial ignition.</strong><hr></blockquote>

I thought I could let this topic ride, but its been bugging me and I just have to give it one last go.

Remove the cannon from the frame and move it around, applying inertially tangential forces to the toggle train. The toggle stays closed. It is clear that the striker spring provides all the force necessary to keep the toggle train in its locked position, as a connection with the main recoil spring is nonexistent. The recoil spring has no, repeat -no-, effect or function in keeping the toggle train in its proper plane at rest.

--Dwight

[quote]Originally posted by Dwight Gruber:
<strong> Remove the cannon from the frame and move it around, applying inertially tangential forces to the toggle train. The toggle stays closed. It is clear that the striker spring provides all the force necessary to keep the toggle train in its locked position, as a connection with the main recoil spring is nonexistent. The recoil spring has no, repeat -no-, effect or function in keeping the toggle train in its proper plane at rest.
--Dwight</strong><hr></blockquote>

With the striker in the cocked position - as it would be for firing - the force of the firing pin spring is actually pushing back against the breechblock and it takes VERY LITTLE momentum to cause the toggles to pop up. The striker spring pressure actually HELPS to push the toggles up. (In fact, the striker spring does more to keep the train locked when it's NOT cocked as the train has to overcome the drag of the sear and the striker spring pressure to reach the "toggles broken" point.) Turn the cannon over and tap the top of the receiver where the date is normally stamped against the ball of your palm. If the pistol had been designed for zero recoil spring tension on the toggle train when in battery and with only the striker spring pushing back on the train, the design would never have flown and it would be a long forgotten footnote in the history of firearms.

There is NO POINT in the cycling of the action from cocked and locked through opening, ejection and chambering a new round that does not have recoil spring pressure applied to the train. Even with the striker uncocked, there is recoil spring pressure being applied. It's part of the design. If that wasn't true, there wouldn't be pressure of varying weight applied to the train at ALL times by the recoil spring.

Doubs, Good analysis. I concur. Tom H.

Hi Doubs!

[quote]Originally posted by Doubs:
<strong>
With the striker in the cocked position - as it would be for firing - the force of the firing pin spring is actually pushing back against the breechblock </strong><hr></blockquote>
Yes sir, the net effect is as if the striker spring were directly acting against the breechblock. But in reality the striker spring is actually not pressing directly against the breechblock. Rather it is pressing forward against the inside front surface of the striker channel in the striker, and rearwards against the breechblock end piece, which in turn is pressing rearward against the breechblock.

[quote]Originally posted by Doubs:
<strong>
and it takes VERY LITTLE momentum to cause the toggles to pop up.
</strong><hr></blockquote>
Quite right! But whatâ??s happening here is actually quite complicated.

With the striker held at the cocked position the pressure exerted by the striker spring is bi-directional. It is exerting pressure forward against the striker, and rearward against the breechblock (via the breechblock end piece). So long as the toggle pivot point is below the centerline of the toggle train this rearward striker spring pressure on the breechblock serves to retard upward motion of the toggle knobs. But as soon as the toggle knobs have been raised enough to bring the toggle pivot point above the centerline of the toggle train and the rigidity of the toggle train is broken, then the compressed striker spring will fling backwards the breechblock, causing the toggle knobs to jump upwards.

[quote]Originally posted by Doubs:
<strong>
The striker spring pressure actually HELPS to push the toggles up. </strong><hr></blockquote>
Yes sir, it does, but only after toggle pivot point is above the centerline of the toggle train. Conversely, the striker spring opposes forward movement of the toggle train once the teat on the striker contacts the sear and the striker spring begins to be compressed between the inside front surface of the striker channel in the striker and the breechblock end piece.

[quote]Originally posted by Doubs:
<strong>
(In fact, the striker spring does more to keep the train locked when it's NOT cocked as the train has to overcome the drag of the sear and the striker spring pressure to reach the "toggles broken" point.) </strong><hr></blockquote>
Here I have to respectfully and cordially disagree. When the striker in not cocked, it is forward of the sear and there is no sear drag - as there is no contact with the sear. Also, the striker spring is not compressed by the rearward movement of the toggle train. Rather it is compressed by the forward movement of the toggle train after the teat on the striker contacts and is held to the rear by the sear - an uncompressed striker spring provides no spring pressure.
That said the striker, during rearward movement of the toggle train, must pass by the rear of the sear and to do so must push the rear outward. This outward motion of the rear of the sear is resisted by the sear spring, so the inward pressure on the rear of the sear exerted by the sear spring must be overcome by the force being used to draw the breechblock (and the striker it contains) to the rear. Thus the rearward motion of the toggle train is not inhibited by either the striker spring or sear drag, but rather by the sear spring which opposes the movement of the outward movement of the sear to clear the path of the striker as the strike moves to the rear.

[quote]Originally posted by Doubs:
<strong>
Turn the cannon over and tap the top of the receiver where the date is normally stamped against the ball of your palm. If the pistol had been designed for zero main spring tension on the toggle train when in battery and with only the striker spring pushing back on the train, the design would never have flown and it would be a long forgotten footnote in the history of firearms.
</strong><hr></blockquote>
This is true, and I donâ??t think anyone has suggested otherwise.

The point I was making (and this seemed to gotten lost in the discussion fairly quickly {wry smile}) is that the pressure of the main spring pushing the toggle train forward during firing becomes equal to or less than the pressure of the striker spring as the striker spring resists compression during forward movement of the toggle train during firing. At this point in time during action cycling the force acting to bring the toggle train forward is only the momentum of the toggle train, imparted to the toggle train by the main spring before the main spring force was equaled or overcome by the resistance of the striker spring.

[quote]Originally posted by Doubs:
<strong>
There is NO POINT in the cycling of the action from cocked and locked through opening, ejection and chambering a new round that does not have main spring pressure applied to the train. Even with the striker uncocked, there is main spring pressure being applied. It's part of the design. If that wasn't true, there wouldn't be pressure of varying weight applied to the train at ALL times by the main </strong><hr></blockquote>

Again, quite true and not something Iâ??ve ever disputed. Mainspring pressure on the toggle train exists throughout the movement of the toggle train. But this mainspring pressure is countered by, and becomes mechanically insignificant, when the toggle train returns forward sufficiently for the striker spring to resist the forward movement of the toggle train.

Warmest regards,

Kyrie

So long as we are having this debate about the details of which spring does what, let's get the designation right. The striker spring is the mainspring. The recoil spring is NOT the main spring. In any breechloading, caplock, flintlock or snaphaunce firearm, the mainspring is the one that makes it go bang. Hence, in the Luger the striker spring is the main spring. All of these firearms have a mainspring, the majority do not have a recoil spring. In some itty bitty pocket pistols, the mainspring and recoil spring become one and the same spring. I am referring to English terms here without regard to German ones.

It's probably better to refer to them as striker spring and recoil spring and side step the confusion. Referring to the recoil spring as the main spring probably happens because it is the biggest spring. But keep in mind that Thor, unlike us mere soft pawed mortals, is in the habit of shooting the cannon with no recoil spring present. But he is still using the striker or main spring.

The recoil spring exerts a closing force on the toggle train at any and all positions. In the last stages of closing, the striker spring presents an opposing force. It then becomes a balancing act as to which will exert the greater force. Which one dominates depends upon the individual pistol and spring set. Momentum does play a significant role in the final stages of closure, paricularly with a light recoil spring. If deprived of momentum by holding the toggles and allowing them to slowly close, some Lugers will close on spring forces alone, some will not close. Keep in mind this only counts when loading a cartridge. The principal difference is in the strength of the recoil spring.

Minus the recoil spring, the striker spring will tend to keep the action closed when it is in battery and cocked since the "knee" is past center. This is a rather small force though. If not cocked it will have no influence.

When in battery, the closing force of the recoil spring is required to insure that the action is not opened by the random forces of handling or dropping the pistol. This force is of liitle or no significance in keeping the action closed at the time of firing. The back thrust tneds to hold the action closed due to the "knee" being below the center line of the front and rear toggle pins.

In contrast, the Erma Luger look alikes are blowbacks, the knee never goes below the center line and the spring force is absolutely required to keep the action closed in handling. Strangely enough, the spring force is not very significant at the time of firing. here, the inertia of the breech block and toggle train tend to oppose opening and slow it down to the point that the bullet has left the barrel and the pressure has dropped before the action has opened far enough to expose more than the web area of the case. The spring forces are then significant for decelerating the action while momentum opens it the rest of the way.

The spring force is not significant in holding the action closed at firing in the blowback because the backthrust is on the order of several hundred pounds while the force of the spring is a few tens of pounds. The case expands and drags on the chamber walls providing more resistance to opening than the spring does.

As regards the terminology of main spring and recoil spring, Unspellable is, of course, absolutely correct. I know better and should have used the terms correctly. I have edited my post as needed to make it right.

Kyrie is also correct that compression of the striker spring doesn't occur until the toggles move from the "broken" position to the locked position. However, as he also acknowledges, there is friction between the striker and the sear as the toggles raise.

I can't speak for anyone else but this thread has caused me, at least, to consider the working of the action, and the forces involved, more closely than I otherwise would have. It's been an interesting discussion..... and maybe not over yet! [img]smile.gif[/img]

Hi Unspellable!

Iâ??d disagree only with your terminology :-)

Seriously, and in the interests of clarity and of comradeship, may I suggest we use the terminology from the â??Parts and Disassemblyâ?� page on this Forum? I think we may both disagree with the terminology used there, but that terminology has the advantage being easily accessible to all, and is complete with a parts diagram so folks who havenâ??t spent a lot of time inside a Luger can at least see which parts are being discussed.

Just a suggestion :-)

Warm regards,

Kyrie
Moderator - Cruffler_Forum on Yahoo Groups
"The flame free C&R Forum."

[quote]Originally posted by Doubs:
<strong>I can't speak for anyone else but this thread has caused me, at least, to consider the working of the action, and the forces involved, more closely than I otherwise would have.</strong><hr></blockquote>

Hi Doubs!

You speak for me as well :-)

The Luger is a real study in the redirection of force, sometimes around several corners! Perhaps we should discuss the linkage that turns a press on the trigger to the release of the firing pin. The trigger to firing pin linkage is just bizarre, and would please Rube Goldberg ;-)

Warm regards,

Kyrie
Moderator - Cruffler_Forum on Yahoo Groups
"The flame free C&R Forum."

Tom and Dwight,
Yes, I have tried different mags both new and old. I am able to slap the toggle shut. But the artillery fires about 50% of the time properly and the rest of the time it either stove pipes or the spent cartridge is not pulled out of the chamber. Sometimes the gun is not cocked and my simple moving the toggle back about a quarter of an inch cocks it. Because the spent casing often stayed in the chamber I was focusing on dirt in that little notch above the barrels cone that the extractor fits into. But that does not seem to be my answer.
Big Norm

Hi Kyrie,

Recoil spring and firing pin spring as per the parts list suits me. However I notice the associated numbers do no seem to match the exploded drawing. Apparently the numbers do match one or another of the original Luger manuals. Maybe we need a third column of numbers to match the exploded drawing.

If anybody starts a discussion on the trigger linkage, make it a new thread.

Kyrie,

In response to Doubs, you wrote (in part):

"...the striker spring is not compressed by the rearward movement of the toggle train. Rather it is compressed by the forward movement of the toggle train after the teat on the striker contacts and is held to the rear by the sear..."

The second part of this exerpt is good as gold, but the first part is not borne out by the realities of the relationship between the toggle action and the striker. In fact, the striker spring is progressively compressed throughout the entire rearward (opening) movement of the toggle train!

This can be observed by pushing out the rear toggle pin and sliding the toggle/breechblock assembly out of the receiver (barrel extension). One can then see that there is a projection or "ear" at the front end of the forward toggle link which engages the forward end of the striker lug (teat) and begins to cam it rearward, relative to the breechblock, as soon as the toggle knobs have raised by 1/16 inch or so. This camming continues throughout the breech opening, and is of course accompanied by increasing compression of the firing pin spring.

The analytically inclined person will wonder at once why the ear was provided, since its action has nothing to do with the actual cocking of the striker in preparation for firing! I have contemplated at some length why the function exists and discussed it off-line with Johnny Peppers. Between us we came up with a couple of plausible reasons, but perhaps they are best reserved for another time.

Jerry, GREAT observation! As many times as I've manually compressed the firing pin spring by flexing the breechblock and middle link and I completely let that fact slip my mind.

My thought would be that compression of the firing pin spring under recoil is necessary because the recoil spring power plus the momentum of the mass of the train wouldn't be enough to compress the spring reliably - maybe not at all - through engagement of the sear near the end of the cycle when recoil spring pressure would be nearing it's lowest point.

The front toggle extension retracts the firing pin during the back stroke not for the sake of compressing the firing pin spring, but for positive control of the position of the firing pin. You don't want it sticking out of the face of the breechblock during ejection and reloading.

Since, as a side effect, the firing pin spring is compressed, it becomes a part of the overall momentum and spring compression budget.

[quote]Originally posted by Jerry Harris:
<strong>The second part of this exerpt is good as gold, but the first part is not borne out by the realities of the relationship between the toggle action and the striker. In fact, the striker spring is progressively compressed throughout the entire rearward (opening) movement of the toggle train!
</strong><hr></blockquote>

Hi Jerry!

You are absolutely right, and I stand gratefully corrected :-)

Warm regards,

Kyrie

Kyrie,

Thanks for your most courteous reply. Many's the time when I, too, have been grateful for a correction.

Unspellable,

I concur that firing pin control is the strongest reason for the ear's existence. What it accomplishes overall is to enhance safety by positively blocking the pin from contacting the primer at ALL times EXCEPT when the breech is within about 0.050 inch of full closure. Johnny Peppers pointed out that keeping the pin retracted also assists reliable cartridge feeding.

In his E-book on Luger mechanics (I finally got it although there's no version for Macs), Henrotin brings up a very interesting additional function for the ear. He claims that the head of the striker spring guide acts as a shock absorber by contacting the back of the frame and helping to stop the rearward breechblock travel. So the compression of the spring by the ear makes the "absorber" stiffer! Sounds reasonable, but my measurements say the spring force only increases from about 4.5 lbs to 7 lbs via the compression, and the available snubbing stroke can't be more than about 0.07 inch. I have to wonder how effective a snubber it really is.

Doubs,

When I first pondered the ear, thoughts very similar to yours crossed my mind. It is true that the effort expended by the ear in compressing the striker spring will later, as Unspellable implied, feed back as a small additional breech-closing force. But it's so wimpy (won't even overcome friction) that we probably shouldn't count it as an engineering reason for adding the feature.

[quote]Originally posted by Jerry Harris:
<strong> Doubs, When I first pondered the ear, thoughts very similar to yours crossed my mind. It's true that the effort expended by the ear in compressing the striker spring will later feed back as a small additional breech-closing force. But it's so wimpy (won't even overcome friction) that we probably shouldn't count it as an engineering reason for adding the feature.</strong><hr></blockquote>

Jerry, I've pondered Unspellable's points but cannot completely agree that the PRIMARY purpose of the ear is to retract the firing pin to aid ejection and feeding. There are simply too many successful designs that, in the case of submachineguns, use a fixed firing pin or pistols with a firing pin that is pushed back by the new cartridge being chambered. e.g., the VZ-52 pistol.

My point was that the force necessary to compress the firing pin spring from it's rest position to the cocked position can not be reliably done by sear/firing pin engagement in the final movement of the toggle train as it seats the new cartridge and locks. Without the compression being provided on the recoil cycle when plenty of force is available, a reliable cocking and closure would not be possible.

I'm not downplaying the importance of safety or the benefits of the firing pin being retracted as an aid to ejection and feeding. It's just my opinion that they are secondary considerations to reliable cocking of the firing pin and closing of the action. The pre-compression of the spring also lessens the impact of the sear against the firing pin projection.... both somewhat delicate surfaces. Military primer cups are normally made harder than their civilian counterparts so a slam fire isn't likely. If that were not so, fixed firing pins combined with open bolt designs would not be possible.

As for the firing pin spring helping to soften the impact of the toggle train in it's rearward most movement, the firing pin keeper is slotted so that the toggle link to the recoil spring fits into it. The keeper does contact the link but the cushioning affect protects the link from damage due to being pounded repeatedly by an ungiving piece of steel. Any lessening of the recoil forces to the remainder of the train would seem incidental and not the primary reason for the free movement of the keeper. (Datig's book calls the "keeper" or firing pin spring guide the "breechblock end piece" which is too long to use here. Hence "firing pin keeper" or simply "keeper".)

Anyway, that's my opinion and I'm open to being convinced otherwise if the evidence is strong enough.

Different firearms operate in some what different ways, including the exact details of how they feed a cartridge into position.

Most submachine guns are blow backs and many are slam fired. That is, the firing pin is fixed to the face of the breech block and the impact of the closing breech fires the cartridge. Such guns are fired from an "open bolt" position. A design of this sort depends on using blow back operation rather than a locked breech so that the exact position of the breech block (To within thousandths of an inch.) is not critical when the cartridge fires. The feed path must accommodate the fix firing pin protruding from the breech face. The usual design headache with this type of firearm is finding a way to slow down the rate of fire while maintaining reliability.

In the Luger, the feed path is such that with the firing pin protruding from the face of the breech it would block the rim of a cartridge sliding up into position. This is a key point. There was an earlier discussion on this forum about the cartridge sliding up under the extractor rather than the extractor coming forward and riding over the rim. Retaining the firing pin also prevents slam fires.

The firing pins in many of those "other" pistols are restrained by a strong firing pin spring and possibly a firing pin block. The main spring is in the frame and drives the hammer with sufficient force to overcome the resistance of the firing pin spring. The Luger is striker fired and must have the main spring directly driving the striker or firing pin.

I have seen the same article Doubs mentions about the spring guide acting as a snubber. Like Doubs, I am a bit dubious. This is one of the questions on the agenda for my project. I will be rigging tell tales to determine just how far back the action goes and whether the spring guide actually does contact the frame or recoil spring link. Part of the motivation is to determine the proper range of cartridge impulse and recoil spring strength to obtain proper functioning without abusing the pistol.

[quote]Originally posted by unspellable:
<strong>Different firearms operate in some what different ways, including the exact details of how they feed a cartridge into position.

In the Luger, the feed path is such that with the firing pin protruding from the face of the breech it would block the rim of a cartridge sliding up into position. This is a key point. There was an earlier discussion on this forum about the cartridge sliding up under the extractor rather than the extractor coming forward and riding over the rim. Retaining the firing pin also prevents slam fires.

The firing pins in many of those "other" pistols are restrained by a strong firing pin spring and possibly a firing pin block. The main spring is in the frame and drives the hammer with sufficient force to overcome the resistance of the firing pin spring. The Luger is striker fired and must have the main spring directly driving the striker or firing pin.</strong><hr></blockquote>

The breechface of the Luger is recessed and encloses the rim of the cartridge. The cartridge base, therefore, cannot simply slide up the face of the breech and into position for firing. When the next cartridge is stripped from the lips of the magazine, it is being pushed upward by the ramp in front and forward by the lower part of the breechblock. When the bullet comes in contact - forcefully - with the chamber face, there is a mechanical "jump" of the cartridge upward. At the same time, the breech is still pushing forward on the cartridge and forces the nose of the bullet, as it jumps upward, into the chamber. The chamber centers the cartridge and in the final movement of the toggle train into battery, the extractor rides up and over the rim as the base of the cartridge seats in the recess of the breechface. Not until the final few thousands of an inch does the possibility exist for the firing pin to contact the primer. By this point in the feeding sequence, the sear would have engaged the firing pin and retracted it so that no contact would be possible between the pin and the primer... even if the hook wasn't part of the design.

Unlike the 1911 design that has a "controlled feed" - the rim slips under the extractor as it rides upward out of the magazine and is held against the breechface right into the chamber - the Luger does not control the feed of the cartridge and the extractor doesn't engage the rim until the very end. (If you want to break a 1911 extractor, drop a cartridge into the chamber and let the slide go forward. Unless specially modified to do so, the 1911 extractor does not ride over the rim to engage.)

While "inertia" or "rebounding" type firing pins do have a spring in front of them that must be overcome by the hammer, the VZ-52 and other Soviet Bloc designs have no spring on either end of the firing pin. The new cartridge primer pushes the pin back into firing position. The Makarov and the later SKS carbines come immediately to mind.

The design of the Luger firing mechanism, borrowing heavily on the Borchardt design, does several things to the firing pin assembly during recoil. We could discuss for years which is the "most" important or which is truly the "primary" reason for the design being as it is. All of the things it does are important to proper functioning and we'll both still have the same opinions. This has been an educational thread and I've learned a lot from it.

The face of the breechblock is indeed recessed, but this in no way prevnts the cartridge from sliding up the breechface. The cartridge starts to slide up the breechface at almost the same time it begins to enter the chamber. As the cartridge continues up the breechface, it begins to push the extractor up as the back of the cartridge case and the extractor are on the same plane ahead of the breechface recess. As the cartridge moves higher on the breechface it drops into the recess and the extractor snaps down over the extractor groove in the cartridge. The extractor does not jump over the cartridge rim, but actually snaps into the extractor groove as the cartridge seats into the breechblock recess. The cartridge case begins to push the extractor up before the cartridge case is half in the chamber, and the extractor is fully raised before the cartridge is finally seated. This can be fully examined by slowly cycling a dummy round into the Luger chamber.
At the speed of the toggle assembly during firing, there is no way the cartridge itself is going to jump ahead of the breechblock into the chamber and wait on the breechblock and extractor to seat over it.

First, the rim of the cartridge must rise up past the area of the firing pin, the firing pin must be held back so as not to to block it.

Second, the cartridge will be fully centered in the breechblock face before the breech block reaches battery, although by this time the sear has picked up the striker. However, what if the sear is broken and doesn't work? Then the toggle link extension controls the speed at which the striker is allowed to come to rest, possibly preventing a slam fire.

Allowing the breech block to drop on a chambered round will be hard on the extractor in a Luger too. It is not meant to ride up over the rim from the rear as a practice, although it will do so on the odd occasion.

1911's sometimes toss out cases with teardrop shaped firing pin indentations because the barrel began to drop before the firing pin is out of the way. This is generally regarded as a fault in the pistol that requires correction. In the Luger, getting the firing pin out of the way is a positive action on the part of the toggle extension rather han relying on a rebound spring.

On the other hand, since the breech block and barrel remain in line, it would not drag the firing pin over the case head on extraction in any case. There are blowback pistols that actually uses the firing pin as the ejector.

And yes, we are trying to reverse engineer the pistol and read the minds of the people who developed it a hundred years ago. And also, for every hard and fast rule, there is a firearm somewhere that violates it. As in, :There ain't no such thing as an automatic revolver." except that Webley made 'em.

There is still another extension or "ear" scenario which seems to me important for safety: Breech closings may jam with varying amounts of casing exposed. At about 1/4 inch from closure, the sear picks up the firing pin lug and starts the cocking stroke. At the same breech position, the sear plunger gets back under the trigger lever, so the gun will try to fire if the trigger is pulled. Suppose the breech jams with, say, 1/8 inch to go and the user, not knowing, tries to fire the next shot. The partially cocked firing pin will be released and try to hit the primer, but the ear will catch it. This will be true all the way down to 0.050 inch from full closure. So the blowback accident, although it could happen, can't occur with significant brass exposed, thanks to the ear.

Unspellable, your study of snubbing should be interesting. Did you mean Henrotin's article? (See my message to you, 6th up from here). He illustrates his discussion with photos supposedly showing impressions where the firing pin retainer head has hit the frame. He calls that normal and says it's an indicator of how much a Luger has been fired. Evidently the sides of the head reach around the spring coupling link, via the groove in the head, to make contact. I don't see any other possibility.

Jerry,

Unfortunately this idea does not wash. The issue came up previously and there was a thread concerning it. I was running experiments to find the weakest usable recoil spring. The spring must store enough energy to properly carry out the loading operation, this sets a lower limit, and correspondingly, a lower limit on the load used.

With the weakest spring tried, the action occasionally stopped in just the position you are referring to. This raised the question of whether or not it could be fired so I loaded a few primed cases with the action in such a position and pulled the trigger. The Luger will definitely go bang! The amount of brass exposed is academic since the action is not locked and you are already headed for disaster.

This is a hazard to be watched for at any time, but especially if you are playing with soft recoil springs.

Sort of illustrates the difference between experiment and hot stove debates.

The bit about the firing pin retainer hitting the frame came from the electronic Luger book, I don't have it here with me at the office to quote the exact title and author, but I presume we are talking about the same one.

My project arose from the question of what to feed a 7.65 Luger. Factory ammo ain't it. The project seems to keep expanding and begins to look like it will add up to a small book by the time I am done with it. But it will be nice to have some hard numbers on what to feed a Luger and what to have for a recoil spring instead of a lot of conjecture. I am actually measuring recoil spring strength, muzzle velocity, bore diameter, etc., etc.

One fact for preliminary release: You cannot measure muzzle velocity and attempt serious target shooting at the same time. By the time I get the bullet trap lined up on the target I am invariably shooting from some awkward position that is not conducive to accuracy. And the primary point is to launch the bullet in line with the trap rather than the bull's eye. If I had a backyard range I could probably solve this problem, but I am running to the range with a car load of junk and trying to set up a tripod on uneven ground.

Johnny,

The rim and base of the cartridge do not contact the breechface while being fed into the chamber until the final movement of the toggle train places the extractor over the rim. Working the action slowly enough under a magnifier lamp clearly shows a small gap between the breechface and the cartridge. The rim is held away from contact with the breechface by the forward lip of the breech and the cartridge rim rides the lip until the base is square with the breechface. Now the cartridge becomes fully seated in the chamber and the extractor enters the groove. That's when contact with the breechface actually happens.

I've never claimed that the cartridge jumped ahead of the breech or lost contact with it. I said "When the bullet comes in contact - forcefully - with the chamber face, there is a mechanical "jump" of the cartridge upward. At the same time, the breech is still pushing forward on the cartridge and forces the nose of the bullet, as it jumps upward, into the chamber. The chamber centers the cartridge and in the final movement of the toggle train into battery, the extractor rides up and over the rim as the base of the cartridge seats in the recess of the breechface."

I agree that the rim starts to elevate the extractor as the cartridge begins to straighten in the chamber but the extractor does not slip over the rim until the cartridge is fully seated in the chamber and the toggle train is in it's final 1/10th inch of travel. That, too, can be seen clearly if worked slowly enough.


Unspellable,

Because the rim doesn't contact the breechface until the cartridge is square in the chamber and seated, I'm not sure the projection of the firing pin would impede the rim. It looks as though it *might* but I don't have a defective firing pin available to experiment with. As for parts breakage, anything mechanical can and will break. The designer could "what if" himself to death and never produce a thing. They make it as safe as humanly possible and go on.

I don't agree that the Luger extractor would be hurt by repeatedly riding over rims. Looking at the design makes me believe that Georg Luger made it to do just that. He didn't have the advantage of high speed cameras for time and motion studies so it's reasonable to believe that he designed the extractor to slip over the rim as often as necessary. Many of today's best semi-autos have extractors designed that way. The Browning Hi-Power began with a controlled feed extractor but now is made with an extractor designed to slip over the rim.

Doubs,
Without beating a dead horse unnecessarily, apparently we have a breakdown in terminology. The forward part of the toggle assembly is the breech bolt, and the front of the breehbolt is the breech face. On a Luger the breechface is partially recessed. The breechface must contact the cartridge in order to strip it from the magazine.

From your last post:
The rim and base of the cartridge do not contact the breechface while being fed into the chamber

During this stripping process the base of the cartridge rides up the breechface until it reaches the recessed area. As it rides up the breechface it begins to raise the extractor, and as the cartridge seats into the recessed area of the breechface, the extractor slips down over the rim of the cartridge.
I too agree, and thought that was what I said, that the extractor seats over the cartridge rim as the rim seats into the recess of the breechface. I have a feeling that the extractor functions exactly as designed. It will jump over a rim if a cartridge is dropped into the chamber rather than being fed from the magazine, but does not function and was not desighed to function that way during normal operation.

Johnny, you are correct. I don't consider the leading edge of the breechblock to be the "face". Not to be contrary, but, IMO, the face is the part the cartridge base comes to rest against when the action is in battery. If the leading edge of the breechblock and the recessed face are both to be considered the breech face, we now have the same term being applied to two different planes. IIRC, I've seen the term "cone" used to describe the protective collar on the bolt in front of the face. Unfortunately, my reference books on gunsmithing do not explain "breechface" in any detail or when the face is recessed. Perhaps you have a better reference?

All that aside, I believe we both have been explaining the same mechanical actions while disagreeing on the terminology.

Unspellable,

Thanks -- I'm grateful to be corrected and remember your excellent test series.

By construction the ear won't let the tip of the firing pin protrude from the recessed part of the breech face until the breech is within about 0.050-inch of closure (easy to check this by measurement). So no matter what the release point was, the actual instant of your test primer ignitions must have occurred somewhere between 0.050 in. open and locked. I thought the amount of cartridge casing exposed at ignition would affect the degree of danger to the user (less being better), but maybe I'm wrong. I don't think any of us wants to do the test series that would tie that one down!

I certainly don't dispute the fact that a blowback accident could happen, as the last sentence of the first paragraph of my previous (08-22) post said.