Boring vs Sleeving

[unspellable]

Simple experiment: I dropped a 7.63 Mauser case into a 9 mm P08 (Don't do this with a loaded round boys and girls!) and it will not chamber or come close to chambering. As previously mentioned, this indicates the 7.63 Mauser chamber is bigger in some places than the 9 mm chamber so boring one out to 9 mm will not be entirely satisfactory. There will be oversized areas. This change really should be done by sleeving.

On the other hand, a 7.65 mm Parabellum case will chamber in a 9 mm P08 so boring a 7.65 barrel out to 9 mm may be practical.

But here's the offshoot observation. We have long assumed the 9 mm Parabellum was a developemnt of the 7.65 mm Parabellum. Looking at sketches of the early DWM experiments for a 9 mm cartridge and considering the above I am starting to think the 9 mm was developed directly from the 7.65 Borchardt or 7.63 Mauser case and did not derive from the 7.65 Parabellum case as has been generally ssumed.

[Karl]

That would be a major re-write of history! [img]eek.gif[/img]

[John Sabato]

unspellable,

IMHO I am sorry but I can't agree. I think your speculation on the development of the 9mm Parabellum cartridge is a pretty large leap without any historical or definitive engineering documentation to back it up.

[quote]this indicates the 7.63 Mauser chamber is bigger in some places than the 9 mm chamber <hr></blockquote>

No. what this indicates is that the fired and stretched 7.63 Mauser CASE that you used for your test is probably bigger in some places than the 9 mm chamber.

The 7.65 Luger proved to be inadequate stopping power during military acceptance testing compared to the revolvers of the same period. 9mm was the next logical step in enlarging the bore. Boring & rifling the barrel for 9mm would have been a simple operation change. Any other caliber would have required a major tooling and re-engineering change at DWM... This would have been the only logical move for a larger caliber that would fit the existing magazine and mechanicals of the Luger Design... that is why you hardly ever hear of any wildcatting of calibers being done on a Luger chassis...

The 7.65 case was blown out to appropriate dimensions to support the projectile of choice... The fact that all magazines accomodates both calibers strongly supports this theory.

[Hugh]

The postings by Doubs & Unspellable concerning the reboring of 30 Mauser Broomhandles to 9mm aroused my curosity, as I recently had this done by Redmonds. First, let me state that this was the first experience that I have had with reboring and I have no vested interest in Redmonds Reboring. I quote from their brochure:

"When the 7.63 Mauser bore is reamed to 9mm, this reams out the bottleneck of the existing chamber, and what is left of the existing chamber is the correct length and diameter for the 9mm cartridge. No chambering is necessary. This may seem strange, but I have rebored hundreds of these Brooms and I know what I am talking about.
Some Brooms that have been shot out, may have excessive chamber wear at the front of the chamber, which may cause the 9mm case to go too far forward, giving an excessive headspace problem. There are three ways to remedy this problem. If you hand load, longer cases can be used such as the 9mm mag and the cases can be trimmed to the proper length. The other alternative is to control the headspace by seating the bullet out from the case a little longer so as to set the case back against the bolt face taking up the excessive headspace. This method is described by Finn Agaard in an American Rifleman article, Aug.1988, pg.32. If you do not hand load there are various commercial loads that vary in bullet seating and can be matched up to your pistol. To check your Broom for proper headspace, you need to remove the barrel from the receiver and strip the bolt of extractor and firing pin. Insert a sample dummy cart. in the chamber and see if the bolt comes all the way forward, and if it does, check for excessive gap between the bolt face and cartridge. The third alternative is to chamber to 9mm export. I cannot guarantee this cart. to feed properly and some action alternation may be necessary. I do not do any action conversion.
In the conversion of your Broomhandle, I only rebore the barrel and do no chambering. I have no control over your existing chamber and therefore cannot be responsible for its condition."

Contrary to the experiences of Doubs & Unspellable, I experienced no difficulty in dropping a 30 Mauser cartridge in several of my 9mm Lugers and having it chamber easily. According to my micrometer, the shoulder on the new Old Western Scrounger 30 Mauser cases measure .0370" dia. The mouth of my WW 9mm loaded rounds mics at .0375". I fired 5 of these 9mm loads in my rebored Broomhandle, which appears to have no headspace problem. These fired cases measured .0377" at the mouth. The taper remained the same, and there was no bulging anywhere on the case, they looked as if they had been fired in one of my Lugers.

I can only surmise that the problem experienced by Doubs was due to excessive chamber wear in his gun. As for Unspellabe being unable to chamber 30 Mauser in his 9mm, and mine chambering ok, there must be a difference in dimensions of his cases and the ones that I have.
<img src="graemlins/yltype.gif" border="0" alt="[typing]" />

[Roadkill]

I had a similar problem in a Sako .222, got a box of Remingtons which simply would not chamber. And yes, they were the right caliber. Good luck on the Luger frame you are bidding on. Wonder what you would want that for?

RK

(need a box of Remington .32 rimfires?)

[Hugh]

Roadkill,

Hang on to them, never know when you might decide to rebarrel a Looger to that caliber! <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />

[unspellable]

Yes, a fired case has been stretched. But we are talking about chamber size here, not case size. The first case was a Norinco 7.62 X 25 Tokarev case fired in who knows what. I tried the same experiment with two 9 mm Lugers (A DWM and WWII Mauser.) and a 7.63 mauser case fired in my own C98. Same results. Next I pulled the firing pins and tried an unfired 7.63 Mauser round. Same results. None of them came close to chambering. Next I pulled out the cartridge drawings and it?s obvious the Mauser round will not chamber in a 9 mm. The 9 mm case length is 0.754, while it is 0.761 inches from base to shoulder on the 7.62 Mauser. The 9 mm Parabellum is 0.380 in diameter at the case mouth. The mauser case is 0.397 in diameter at this point and to a distance of 0.007 in front of it. (At least going by the drawings in the Lyman pistol reloading book.) It then angles inward at 16 degrees 24 minutes with respect to the center line. It may be possible to get a 9 mm round to sort of headspace somehow, but not really correctly. Bottom line is, I would not ream a 7.63 chamber out to 9 mm. If I had to make the conversion, I?d sleeve it.

Now as for the derivation of the 9 mm Parabellum. John Sabato puts forth the incentive for doing it, not the actual development process. Now I am not claiming the cartridge derives directly from the 7.65 Borchardt or 7.63 Mauser without the intermediate step of the 7.65 Parabellum, but I am saying the idea merits consideration.

First there was the 7.65 Borchardt. Then came the 7.63 Mauser with no significant dimensional changes, only a hotter load. Then came the 7.65 Parabellum, (circa 1898) a shortened version of the Borchardt. I think everyone will agree up to this point.

The first 9 mm Luger cartridge was DWM case 480, a bottle necked case loaded with a round nosed bullet with a fairly blunt ogive like the 455 Webley auto. The second 9 mm Luger cartridge was DWM case 480A, similar to the first one. The Luger DWM tried to sell to the British military (circa 1902) was chambered for one of these bottle necked cartridges. These cases were longer than the 9 mm Parabellum case (I will use the term 9 mm Parabellum to refer to the final development as we know it today.) These cases have every appearance of being a necked up and shortened 7.63 Mauser case rather than a necked up 7,65 Parabellum case. They do not have the tapered sides of the 7.65 Parabellum and are a bit long for such a conversion. The next attempt was DWM case 480B, a straight case, and as such, outside the entire Borchardt derived family. (Smaller head.) The fourth case, 480C, was a tapered case and became the 9 mm Parabellum. Now it is conceivable that you could neck up a 7.65 Parabellum case to achieve it, but it would be simpler to trim the front off a 7.63 Mauser case and you have the 9 mm Parabellum case with almost no resizing at all. (Keep in mind they all have the same head except case 480B.)

Now speculating as to which led to who is admittedly shaky, we are trying to read the minds of the guys in DWM?s back room a hundred years ago. They would have had all these cases lying about. I?d not be surprised if Georg Luger himself would have difficulty in saying which one led to which. Keep in mind we are not converting brass of one size to another where it?s all clear cut. This is cartridge development with dies for each version and only the head in common, so things are a bit fuzzier as far as saying which derived from which.

Granted, this is all speculation, but that?s where any new hypothesis starts.

One other point, Luger?s magazine design is a bit tricky. If you haven?t noticed, it?s handling cartridges that are longer then the magazine itself is. The cartridges do not stack on each other like they do in most magazines. The rim rests on the case below it while the bullet nose rests on the front of the magazine. They are tilted in the magazine with the nose higher than the base. This trick allows tapered cases, longer cartridges, and the back slanted grip we all love. It?s not so good for feeding hollow points with a big opening and a sharp edge. The edge of the hollow snags on the front of the magazine. But it will handle long cartridges.

[Hugh]

Unspellable,

You stated:

"I pulled the firing pins and tried an unfired 7.63 Mauser round. Same results. None of them came close to chambering. Next I pulled out the cartridge drawings and it?s obvious the Mauser round will not chamber in a 9 mm."

"The 9 mm Parabellum is 0.380 in diameter at the case mouth. The mauser case is 0.397 in diameter at this point and to a distance of 0.007 in front of it. (At least going by the drawings in the Lyman pistol reloading book.)"

What brand of 30 Mauser brass are you trying to chamber in your 9mm's? I am using new brass from Old Western Scrounger with a 93 gr bullet handloaded to 1.36" oa length with no resizing of the brass. I tried these cartridges in a 1915 DWM, a 1918 DWM, a 42 byf, a 1936 S/42, and a 1923 Commercial. They chambered fine with no problem in all of these 9mm guns. The shoulder diameter on these cases is .370" and they measure .760" from base to shoulder.

It seems that even the "experts" can't agree on the dimensions of the 30 Mauser!. I got the following dimensions from my books: HANDBOOK OF CARTRIDGE CONVERSIONS BY John Connelly; 7.63 Mauser shoulder diameter=.370", length to shoulder=.735". 9mm Luger neck dia=.380, case length=.754'. DESIGNING & FORMING CUSTOM CARTRIDGES by Ken Howell; 7.63 Mauser shoulder diameter=.372", length to shoulder=.760" 9mm Luger neck diameter=.380", case length=.754". CARTRIDGES OF THE WORLD, 7th ed; 7.63 Mauser shoulder diameter=.370", 9mm Luger neck diameter=.380". <img src="graemlins/soapbox.gif" border="0" alt="[soapbox]" />

[unspellable]

Hugh,

The loaded Mauser cartridge was a Hansen. The brass fired in my C96 was from the same box. When I get home tonight I'll check this out with a few other brands.

Off hand, your Mauser brass sounds wrong. If the shoulder has that small a diameter you must have a tapered case. The 30 Mauser (or Borcardt) is supposed to be a straight case. It's actually not perfectly straight but the taper is much less than on a 7.65 mm or 9 mm Parabellum. The Borchardt and C96 have vertical stacker magazines so the cartridge was designed with very nearly straight sides. The trick magazine in the Luger allows the use of tapered cartridges for easier extraction. Tapered cartridges are normally associated with bannana magazines or double stackers that are narrower in the front. Not that there aren't exceptions, but that was the original intention.

But you are right, there are a lot of different versions, variations, and stories floating around. Witness the debate over whether the 6.63 Mauser and 7.62 Tokarev are or are not identical. Are any observed differences intentional or just manufacturing tolerances?

I have a rifle chambered for 400-360. Everything you can find for diminsions on this cartridge in the Handbook of Cartridge Conversions is absolutely dead wrong. Turns out there are five different non-interchangable 400-360's. The book mixes the rim thickness from one, the base diameter from another, the bullet diameter from a third, etc.

[Doubs]

At the risk of being all wet, I'd like to make a couple of comments about Luger cartridges.

The 7.65mm or .30 Luger cartridge is, of course, a bottle neck design. The smaller front portion of the bullet/neck part makes feeding similar to throwning a marble into a tin can. The chamber mouth is huge in comparison to the front part of the cartridge and, once the small front has entered the chamber, it guides the larger body into the cavity. Providing that the cartridge is powerful enough to work the action, jams with the .30 Luger cartridge are rare.

Now comes a demand from the German military that a larger diameter bullet is required because the 93 grain bullet of the 7.65mm is inadequate in stopping power. (This was also a criticism leveled by the US Troop Trails reports.) Suddenly, the diameter of the bullet almost fills the chamber mouth and reliable feeding becomes a problem that wasn't a concern with the bottle neck cartridge.

It's always been my personal theory that the taper of the 9mm case was an intentional design feature to facilitate more reliable feeding and functioning of the pistol. The test bottle neck 9mm cartridges may have been an attempt to permit a straight side case with the feeding reliability of the .30 caliber cartridge.

On another point, in my experience the problem with cartridges in the Luger mag have generally centered around the bullet snagging on the mag catch hole. The design of the bullet nose; the bullet nose material and OAL of the loaded cartridge all seem to play a role in how well the cartridge feeds up through the magazine.

Finally, Hugh may well be correct in thinking that my problems with the C-96 that I had rebored to 9mm resulted from a badly worn chamber. The pistol was one of the shot-out Chinese imports and it certainly had seen better days.

These are just a few random thoughts that I thought I'd share.

[John Sabato]

Hey Hugh!

Not having attempted this operation myself except on .22 caliber rimfires during my gunsmithing days over 2 decades ago... Just theoretically, I would think that this operation would best be accomplished by boring and sleeving the entire length of the barrel and then cutting a new chamber and bullet ramp.

As I recall, gunpartscorp.com (numrich) used to sell barrel liners in both .357 and 9mm and they were inexpensive.

If you could get one of those type liners, or just turn an appropriate length of any kind of 9mm barrel (say from a sten or uzi submachinegun barrel stub, or a .357 Dan Wesson revolver barrel)I would think that this would be an interesting project to attempt on one of the shot out barrels you have removed during a barrel replacement...

I would love to hear your thoughts on this...

[Hugh]

<img src="graemlins/nono.gif" border="0" alt="[nono]" />
John,

My thoughts are: "I got too many danged projects in the fire now to even THINK about another one!" <img src="graemlins/c.gif" border="0" alt="[ouch]" />

[unspellable]

Ok Boys and Girls!

We got out four 9mm Lugers, 2 DWM's and two vintage mausers.

We got out six flavors of ammo, Hansen 7.63 Mauser, Fiocchi 7.63 Mauser, S&B 7.62 Tokarev, Winchester 7.62 Tokarev, Norinco 7.62 Tokarev, and some 7.62 X 25 military surplus of uncertain origin.

No mallet.

No permutation or combination of the above would chamber or allow the action to fully close. Might have been able to do it with a mallet but I ain't going that far!

I'll still say that you can bore a 7.63 Mauser out to 9 mm, you can make it go bang, you can headspace it on the bullet ogive, but you can't make it right. Sleeve it.

[Herb]

Not having ever done any of these things I understand what you guys are talking about. If anyone is interested, last week while surfing the Luger wave I found and article written by someone that said that the 03 Springfield rifle barrel fit the Luger perfectly, threads were identical, same twist depth, etc. If so maybe this is an alternative to expensive boring and sleeving, just cut that sucker down to length and have it turned on a lathe to and acceptable diameter and design. I can't verify this but the bore diameter should be close enough to work???

[Edward Tinker]

Hughs artillery from last spring he picked up and Thor redid had a Springfield barrel on it. Looked a bit odd, then Ted did his magic and it was sweet?

Isn't that how I remember it guys?

[John Sabato]

The springfield barrel may be the right diameter but the threads are no where near the same as a Luger. Just from memory (more than 20 years ago) the threaded shank on that barrel is much larger than a Luger threaded shank and the threads are square, not the 55 degree threads on a Luger barrel.

Also, don't forget that the chamber in an '03 barrel is already 30-06 so the threaded portion would have to be totally cut off in any event and rethreaded, rechambered and tapered and the front sight base machined on the end...

I suspect that the piece of 30 caliber rifle barrel that was used on the gun Thor reworked came from in front of the chamber and then was threaded and cut to length...

[Hugh]

[img]eek.gif[/img] Here is the 8" 30 Luger that Ed referred to. Rebarreled by Hugh and refinished by Thor. Note that it is 1923 Commercial "safe" & "loaded"! Seems a '06 bbl would make a good "bull target bbl" if the original contour was kept.

[Johnny Peppers]

Just happened to have a 1903 Springfield barrel handy, and without digging out a mike, the B&S dial caliper indicated 1.038 OD for the thread diameter. Anyone that can screw that into a Luger frame is an accomplished gunsmith. I think someone mentioned that the .30-06 chamber would also be a problem.

[unspellable]

I've heard of using a chunk of '06 Springfield barrel on a Luger before. The nominal groove diameter is 0.308 which is 0.003 undersized. But then many of the available bullets for the Luger, either in factory loads, or for handloading, are also undersized. So everybody goes home happy.

Comes down to know your barrel and use the appropriate bullet.

(Unspellable- your accidental double posting was deleted by me...John S. You could have edited the content, but only moderators can completely delete a post)