Chambering Problems

[Sieger]

Dwight:

If you compair a Luger's chamber to that of, let's say, a P-38's, you will note that the P-38's is almost a sloppy fit compared to a Luger's.

Headspacing on the Luger is precise and somewhat tight, just as it should be.

Question: Do the late model Inter-Arms Mauser Parabellums still have the step, chamber feature?

Sieger

[rabbrt2]

I feel better that the "problems" I observed may not be a indemic to to my Luger!

I have ordered some Mecgar magazines and some Cerro safe to make a mold of the chamber. I will also try different ammo as suggested.

Boy this forum is such a great learning tool! Thanks to all for the feedback.

Robert

[Johnny C. Kitchens]

There is a reason for the step in the 9mm chamber. The round headspaces off of the mouth of the case. As far as a precise measurement of the magazine, no problem. I've got a set of calipers. I've got four different kinds of magazines, so here are the measurements.

My FXO - 1.069"
Swiss - 1.0695"
70's Mauser - 1.065"
Mec-Gar - 1.0625"

I measured from the middle of the back of the magazine to the middle of the curve in front, inside to inside dimensions. Interesting variations...

[Sieger]

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Johnny C. Kitchens:
<strong>There is a reason for the step in the 9mm chamber. The round headspaces off of the mouth of the case. As far as a precise measurement of the magazine, no problem. I've got a set of calipers. I've got four different kinds of magazines, so here are the measurements.

My FXO - 1.069"
Swiss - 1.0695"
70's Mauser - 1.065"
Mec-Gar - 1.0625"

I measured from the middle of the back of the magazine to the middle of the curve in front, inside to inside dimensions. Interesting variations...</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Johnny:

Well then, it sounds to me like Mec-Gar has, indeed, shortened up the interior of the magazine to address the Step-feed problem with modern spec ammo!!!

Original OAL for Ball Ammo 1.175
Current American Standard 1.169
-----
Difference 0.006
=====

FXO Interior Length 1.069
Mec-Gar Interior Length 1.0625
------
Difference 0.0065
======

This little discovery may be very, very helpful to those experiencing the infamous OAL problem. They should now confine themselves to firing ammo that is max. spec. length, that being 1.169 inches long.

As I've said, I have two of these magazines on order and will have plenty of time to experiment with them very shortly.

THANKS A MILLION!!!

Sieger

[Sieger]

DWIGHT:

"At the risk of repeating myself enough times to bore everyone to death, I shoot Walmart Winchester, S&B, and CCI Blazer in three different Lugers (sometimes a fourth, if I break out my nickel-plated byf) with 100% reliability, somewhere between 400-600 rounds a month depending on how often I get to the range."

PLEASE FEEL FREE TO BORE THE HELL OUT OF US ANY TIME YOU LIKE. YOU MAY HAVE JUST SOLVED ONE OF THE MOST ANNOYING PROBLEM WE SHOOTERS HAVE WITH THE LUGER, THAT BEING THE OAL PROBLEM!!! <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" /> <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" /> <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

"I use Mec-Gar magazines almost exclusively, and this probably has something to do with it (my magazine tests revealed that most of my original mags malfunctioned with anything I put in them)."

Can you give us precise measurements of the OALs of your Winchester, S&B and Blazer ammo? <img border="0" alt="[thumbsup]" title="" src="graemlins/bigok.gif" /> <img border="0" alt="[thumbsup]" title="" src="graemlins/bigok.gif" /> <img border="0" alt="[thumbsup]" title="" src="graemlins/bigok.gif" />

Sieger

[unspellable]

Johnny, the cartridge does not headspave on the step. The step is 14.1 mm from the breech face while the headspace is 19.1 mm at the step between the end of the chamber and the beginning of the barrel. A point to note is the SAAMI max case length is 19.15 mm, another point of discrepancy.

So I am still wondering if they went to the straight tapered case but retained the original bottle necked chamber. The bottle neck was very slight.

At the risk of being called an iconoclast, I have a theory that the 9 mm round was developed directly from the 7.65 Borchardt/7.63 Mauser case without the 7.65 Parabellum case being involved, as opposed to the more usual theory that the 9 mm is a necked up 7.65 Parabellum case.

[Sieger]

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by unspellable:
<strong>Johnny, the cartridge does not headspave on the step. The step is 14.1 mm from the breech face while the headspace is 19.1 mm at the step between the end of the chamber and the beginning of the barrel. A point to note is the SAAMI max case length is 19.15 mm, another point of discrepancy.

So I am still wondering if they went to the straight tapered case but retained the original bottle necked chamber. The bottle neck was very slight.

At the risk of being called an iconoclast, I have a theory that the 9 mm round was developed directly from the 7.65 Borchardt/7.63 Mauser case without the 7.65 Parabellum case being involved, as opposed to the more usual theory that the 9 mm is a necked up 7.65 Parabellum case.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Dear Unspellable:

I just read last week that there were two reamers involved in the chambering process. Why this was done...?

Well, the practice persisted from 1902 through 1942 so the German Engineers must have had a good reason for it.

For the origins of the 9mm casing, study Luger's 480 and 480A casings, as these were, indeed, bottle neck 9mms.

Sieger

[Dwight Gruber]

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Sieger:
I just read last week that there were two reamers involved in the chambering process.[/QB]</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Sieger,

Where did you come across this?

--Dwight

[Dwight Gruber]

I'm afraid that I don't have the tools to precisely measure the oal of the Winchester, S&B, or Blazer ammunition.

I would like to take a dissenting position to the theory that overall length of the cartridge in the magazine is the primary contributor to Luger malfunction in the 21st century. I am of the opinion that the condition of the magazine feed lips is the crucial factor, and the magazine spring is an associated consideration (as may be bullet shape).

Earlier in this discussion I reported my experiments with magazines and ammunition, settling on the MecGar magazines and ammunition selection which functions best in my variety of shooting-quality Lugers. This was entirely a methodical empirical test.

The original magazines I tried were a random selection which had come with various Lugers I have purchased. Observing these loaded magazines, it was apprarent that the feed lips had variously become weak or bent, that the topmost cartirdge was not held firmly in position, or was not held at the proper angle. And feed angle seems to be the crucial parameter here, if the bullet nose does not approach the breech precisely, it will misfeed.

Having magazines and ammunition which work acceptably might be the end of the matter, except for some experiences I have had since.

I obtained an fxo magazine (until I traded it) which I used to shoot, along with my Mec Gars, and it proved just as reliable. fxo mags are extruded metal, very solid, and have very stiff feed lips.

I recently picked up a proper magazine for my S/42 shooting Luger, blued metal (rolled&folded) tube, aluminum base. Although I did not buy it as a shooting magazine (judging by my previous experience), I have used it several times with no reliability problems.

If the oal of the ammunition was the primary factor, one would expect these magazines to fail as much as the original mags in my first test. In fact, conventional wisdom has it that fxo magazines are excellent shooting magazines.

With one Luger purchase I acquired another aftermarket magazine, not a Mec Gar, in fact I can't find any manufacturer on it. It is fairly leightweight, and only holds seven rounds. I have compared it to a Mec Gar, and it seems to be the same internal length.

I tried using this magazine shooting several times, suffering malfunctions each time. I looked at it closely and noticed that the feed lips were spread a little, allowing the cartridges to rest at too steep an angle. I unloaded it and pressed the feed lips against the shooting bench (did I mention that it is lightweight?) which bent them in a bit. I re-filled the magazine and noticed that the cartridge angle was better, and proceeded to use it without problem. It has functioned without malfunction ever since.

There are some other magazine variables which affect the angle of the cartridge as it enters (or doesn't enter) the chamber. Take all of your magazines and insert one round, then compare the angle which the magazine follower holds this round. This may have an effect on the availability of the last round to chamber reliably, or even be picked up by the breechblock.

The magazine spring obviously has an effect on the angle the top cartridge rides in the feed lips, as it presses the round more or less firmly into place.

As I have been working with magazines while writing this post, someting else has occurred to me. Some magazines work much more smoothly than others, which has an effect on how strongly the spring presses the cartridge into the magazine lips, and also has an effect on how easily the ammunition stack moves up the magazine. This seems to be independent of ammunition, and has
more to do with follower fit and smoothness of the inside of the magazine tube. It may be that this phenomenom is masking itself as a cartridge overall length problem.

--Dwight

[Sieger]

Dwight:

You have presented quite a detailed analysis here. Now let me challenge it while defending my position.

Given that a magazine is not bent, the spring in it is not too weak, the follower is not catching on the interior of the magazine and the magazine is in otherwise perfect condition, try the following simple test:

1)Load 8 rounds of round nose ball to 1.10 OAL.

2)Load 8 rounds of round nose ball to 1.175 OAL

3)Fill the magazine.

4)Work the action by hand until the magazine is empty, noting how smoothly or roughly the action works with each test length. Take careful note of how the first three rounds "feel" when feeding.

Try your visual check of the first three rounds, noting how they sit just a split mm or so before they engage the lips of the magazine. Are they parallel to the lips or are they canted downwardly?

The short loaded cartridges will cant slightly downwardly. This is the essence of the AOL problem, as the cartridges ride up the inside of the magazine by touching it with their bullet tips and cartridge rims. Please note that a Luger's magazine is shorter inside than the average cartridge, thus causing them to step-feed up the magazine.

I wish curing the jamming problem were as easy as relacing a worn magazine. If this were the case, there should be no jamming Lugers out there today, as a new excellent quality magazine costs less than $20.00.

Sieger

[Dwight Gruber]

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Sieger:
<strong>Try your visual check of the first three rounds, noting how they sit just a split mm or so before they engage the lips of the magazine. Are they parallel to the lips or are they canted downwardly?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">I have four magazines in fromt of me: an original Erfurt armorer's replacement, an original unmarked commercial, the no-name aftermarket noted above, and a Mec-Gar. With three rounds of Winchester in each magazine, they all exhibit the tilting phenomenon equally.

However, I notice this: the top cartridge tilts down until the the nose of the bullet contacts the front of the magazine at the point it is cut out. When the cartridge continues down the magazine, it resumes the orientation it had when it was in the feed lips--tilts back up. All four magazines exhibit this as well.

It works this way with S&B, as well--I don't have any Blazer to try right now.

--Dwight