Extra step in chamber: Has anyone seen this before?

NH Photo Shooter · 01-11-2016, 09:09 PM

I have a 1920 commercial with sear safety, likely made late 20's with likely modifications later. I've been shooting it quite a bit - fun pistol indeed.

I was having way too many failures to feed, and have been working on that. The mags were hanging too low. The mag release showed no sign of excess wear, so I am assuming it was mismatched to the gun. Fixed that, and it helped. Got a Mec-Gar magazine, and that also helped.

The other thing I noticed was that a fair number of rounds were feeding almost all the way, but the bolt stopped about a quarter of an inch from battery. Upon recent close examination of the chamber, I noticed an extra little step about that far back from the step that the case headspaces on. Not large, bit quite visible, and easy to feel with a sharp probe. Testing by manually inserting rounds into the chamber of the stripped gun, with the rounds angled as they would be in feeding from the mag, I could easily see this causing the problem I was having. I polished most of it out with 220 grit on a 3/8" dowel in a drill, going very slowly. It's not quite gone, but I definitely took the edge off. This also had the effect of polishing the chamber rather nicely, and possibly enlarging it by a very small amount. It's feeding much more reliably now.

I have new springs on order from Wolff just in case a weak mainspring was contributing to the issue, but, really, I'm not dissatisfied with the reliability at this point: one or two minor failures (had to tap the toggle down) in over a hundred round test with mostly handloads.

So what I wonder is, has anyone ever noticed this before? Bad chamber reaming, or was that little step there for some reason? I'm assuming careless machining, but wonder if anyone has had any similar experience.

Thanks in advance for any thoughts.

Ron Wood · 01-11-2016, 10:34 PM

The chamber step is a feature of the original design of the 9mm Parabellum, going back to 1903. It was included in 9mm P08s until 1940-41 when Mauser eliminated it, making the chamber in one machining step rather than two. The step was intended to act as a gas seal when the cartridge case expanded upon firing, keeping the greater part of the chamber free from powder fouling. Mauser eliminated the step primarily for two reasons, the introduction of steel cased ammunition and it made machining easier.
Ron

mrerick · 01-11-2016, 10:40 PM

I am afraid that that the stepped chamber is part of the Parabellum's design.

It's a desirable feature involved in helping achieve a more effective gas seal for the 9mm straight walled cartridge.

It was expensive to manufacture, and later Lugers sometimes eliminated this feature.

Hard to say what the result of your modifications will be...

The cycling and cartridge feeding of a Luger is a achieved through a complex balancing act. The magazine is the first place to look when experiencing feeding problems. Replacement with a modern MecGar mag is a wise first step.

Sometimes the wrong recoil spring has been installed in a Luger, which changes the cycle timing. While your 1920 commercial 9mm gun used a 18-19 coil recoil spring of medium pressure, later Mauser Lugers used one with 20-21 coils and more pressure.

Sometimes Lugers can be ammo sensitive. Always use standard velocity 9mm 115gn or 124gn jacketed ammo.

DonVoigt · 01-11-2016, 10:42 PM

I do believe you said the magic words: "mostly hand loads".
They were quite likely just a bid oversize and slightly belled perhaps, or at least the ones that didn't feed well.

Polishing surely didn't hurt, except the chamber is no longer "original"; should that make any difference.

Sergio Natali · 01-12-2016, 03:34 AM

Since here all P.08 are rebarreled many of them have been modified too, in fact I know that some people though that step was some sort of chamber fault.

NH Photo Shooter · 01-12-2016, 08:02 AM

Great information! Thank you all very much!

It wasn't just the handloads that were exhibiting this phenomenon. Several brands of standard velocity commercial 115 and 124 grain ammo were doing this also. I also suspected that insufficient taper crimp might be at fault, but careful inspection and measurement with vernier calipers established that there were no dimensional differences in this area between my handloads and commercial ammo.

So, it appears that I have compromised (not completely removed as yet) a factory "feature". Given the way I did it, I don't think I narrowed the chamber dimension at the end of the case. In order to prevent screwing up the headspacing, I mounted the 220 grit wet-or-dry on the dowel a bit back from the end, which was too large to pass into the throat. I also kept the whole arrangement moving a bit in and out. So I am guessing I partially turned the step into a taper, or maybe just took the hard edge off of it. I have to believe that polishing the chamber helped also.

At any rate, the cases are not coming out any dirtier than they were before, and the gun feeds a lot better, both with handloads and commercial loads.

Still, it's good to know that the issue wasn't being caused by crap machining, and I thank you guys again for the information.

The next step is checking the mainspring against replacements from Wolff to see if that makes any difference. The spring set from them is literally "in the mail".

I won't do any more after that, as the reliability as it is now is acceptable for a range-only gun, especially one that old.

mrerick · 01-12-2016, 08:32 AM

Glad that you have experienced improvement...

Remember that the high precision and hand fit work involved with Luger manufacture made it a very expensive pistol at the time it was being manufactured. In fact, that is how Fritz Walther unseated the Luger with his P.38 (which cost less to make, and was double/single action).

Marc

alvin · 01-12-2016, 09:01 AM

Sounds like a marginal main spring issue. Replacing old spring with a new one should resolve the problem. Please keep us posted.

NH Photo Shooter · 01-12-2016, 01:38 PM

Quote:

Originally Posted by alvin

Sounds like a marginal main spring issue. Replacing old spring with a new one should resolve the problem. Please keep us posted.

I will keep you up to date. I put another 90 rounds or so through it this morning. I must say, this is one accurate pistol!

The first 50 rounds or so were my handloads: 124 grain Berry's Plated RN over 4.0 grains of Bullseye with a CCI 500 primer loaded into mixed range brass on a Dillon RL550. There were no malfunctions for the first 40 rounds or so. Then the odd failure to go into battery as described above began to crop up sporadically. Shifting to factory ammo didn't make a difference (4 different brands). The occurrence of the exact problem described in my original post became more frequent as I kept shooting, regardless of the ammo. There were no other types of failures of any kind, nor have there been in my last several shooting sessions with this pistol.

I see two possibilities: limp wristing as I got tired (which I doubt, as I was especially working on not allowing that to happen), or more challenging feeding as the chamber got dirty. In either case a more powerful spring would help. I ordered the standard 36 pound spring and a 38 pound extra power one. I would hesitate to use the 38 pounder out of respect for the age of the gun.

I'm a bit frustrated with the Post Office. The Wolff spring kit was shipped Monday morning first thing by priority mail, and the tracking number didn't even show valid until this morning, and has shown no progress after arriving in Philadelphia. Should have had them Fedex it.

One simple solution is not to expect this antique to be a range workhorse: keep the round count down and take a Glock or Sig to the range for long shooting sessions.

Anyway, I'm rambling. I will keep you all posted with the Readers' Digest version henceforth.

ithacaartist · 01-12-2016, 02:17 PM

[QUOTE=NH Photo Shooter;282895
I'm a bit frustrated with the Post Office. The Wolff spring kit was shipped Monday morning first thing by priority mail, and the tracking number didn't even show valid until this morning, and has shown no progress after arriving in Philadelphia. Should have had them Fedex it.[/QUOTE]

I've been feeling your 'Postal Pain" for several weeks. I mailed a parcel containing $80 worth of Erma parts to a buyer in Iowa on the 15th of December. For the entire period, tracking said only that it had left my local P.O. I initiated a trace for it last week, which apparently dislodged it from wherever it was "stuck", and it was finally delivered today--2 days short of an entire month for its journey.

Sergio Natali · 01-12-2016, 02:33 PM

I see wherever we live we all feel more or less the same.
Some days ago I ordered two Coltwood grips and I felt exactly like that waiting for the postman every morning. The funny thing is that as soon they were delivered I rushed like hell to put them on straight away!

rhuff · 01-12-2016, 02:41 PM

You may well find that a new, correct mainspring will solve your problem. As a spring undergoes compression and release, it will heat up somewhat, and if the spring in your Luger has reached the end of it's livelihood, it will begin to fatigue, and become less efficient. A Luger is such a balancing act of springs, mag, and ammo.

Also check the feed ramps on the frame and barrel to be sure that they are smooth so as not to slow down the feeding cycle. Good luck!!

DonVoigt · 01-12-2016, 03:05 PM

"I ordered the standard 36 pound spring and a 38 pound extra power one. I would hesitate to use the 38 pounder out of respect for the age of the gun."

I believe you have it backwards, a stronger spring will save the old pistol from "battering" better than the weak one. A lighter spring would only be correct with lower power loads, JMHO.

I'd go for the 40 lb!

But just an observation- when I ordered a set of springs from wolf, 36-38-40,
I fully expected them to be different numbers of coils and/or different wire guage and or different lengths. When they arrived, they were all the same wire guage, two were exactly the same length, and one was a little longer, but all had approx. 20 coils. The 36 and 40 were the same and the 38 longer. I have no way to measure the tension, but it is on my list to make something!

It would be interesting to know what you get.

You may have seen the chart attached; it seems the Germans could not decide which spring to use either!

(Obviously they used a different method to determine the "poundage".)

NH Photo Shooter · 01-12-2016, 03:26 PM

Quote:

Originally Posted by ithacaartist

I've been feeling your 'Postal Pain" for several weeks. I mailed a parcel containing $80 worth of Erma parts to a buyer in Iowa on the 15th of December. For the entire period, tracking said only that it had left my local P.O. I initiated a trace for it last week, which apparently dislodged it from wherever it was "stuck", and it was finally delivered today--2 days short of an entire month for its journey.

Oh, thank you. I feel much better now.

NH Photo Shooter · 01-12-2016, 03:29 PM

Quote:

Originally Posted by luger.parabellum

I see wherever we live we all feel more or less the same.
Some days ago I ordered two Coltwood grips and I felt exactly like that waiting for the postman every morning. The funny thing is that as soon they were delivered I rushed like hell to put them on straight away!

Of course you did. So would I. Wouldn't any half respectable gun nut? When my springs get here they'll be in the gun and at the shooting range before the mail deliverer is off our street! Oh yeah!

NH Photo Shooter · 01-12-2016, 03:31 PM

Quote:

Originally Posted by rhuff

Also check the feed ramps on the frame and barrel to be sure that they are smooth so as not to slow down the feeding cycle. Good luck!!

Did that almost first thing. SOP with a new to me semi-auto pistol. That and a few other things.

NH Photo Shooter · 01-12-2016, 03:37 PM

Quote:

Originally Posted by DonVoigt

"I ordered the standard 36 pound spring and a 38 pound extra power one. I would hesitate to use the 38 pounder out of respect for the age of the gun."

I believe you have it backwards, a stronger spring will save the old pistol from "battering" better than the weak one. A lighter spring would only be correct with lower power loads, JMHO.

I'd go for the 40 lb!

But just an observation- when I ordered a set of springs from wolf, 36-38-40,
I fully expected them to be different numbers of coils and/or different wire guage and or different lengths. When they arrived, they were all the same wire guage, two were exactly the same length, and one was a little longer, but all had approx. 20 coils. The 36 and 40 were the same and the 38 longer. I have no way to measure the tension, but it is on my list to make something!

It would be interesting to know what you get.

You may have seen the chart attached; it seems the Germans could not decide which spring to use either!

(Obviously they used a different method to determine the "poundage".)

Yes, I did see your chart, and thank you for posting it, and posting it again here. Very interesting.

I'm thinking now what I'll do first is try the different springs to see if I can feel any difference from what's in it now when cycling the action by hand. If the 36 feels any different at all, I'll try that first at the range, since I am using relatively light loads. If that doesn't work, I'll see if the 38 does any better. It's a process.

rhuff · 01-13-2016, 02:55 PM

During your "testing phases", I would do all of the testing with factory std. velocity 115-124gr FMJ ammo. Once you get the reliability to your satisfaction, then match your handloads to the factory ammo. I, also, handload for my lugers, but test only with factory ammo.....just a thought.

NH Photo Shooter · 01-13-2016, 04:53 PM

Quote:

Originally Posted by rhuff

During your "testing phases", I would do all of the testing with factory std. velocity 115-124gr FMJ ammo. Once you get the reliability to your satisfaction, then match your handloads to the factory ammo. I, also, handload for my lugers, but test only with factory ammo.....just a thought.

It's a good thought. I think first I'll try testing with both at the same time, as I have been doing. So far I haven't seen much difference in performance. If, however, it must be "adjusted" to any one load type, I'd prefer it be my handloads, as I shoot them out of other guns and they work very well. If that doesn't work, I'll tune it to a particular brand and weight of factory fodder, and only shoot that out of it. After all, that's what the original design was meant to do: shoot one load and one load only. Of course that would mean not shooting it all that much, which is probably wise anyway. It's not what would be considered a collector grade Luger at this point, but it's bound to appreciate in scarcity and value with time, assuming I don't screw it up or wear it out.

The new springs are sitting in my mailbox, delivered at 1612 hours Eastern time. And my back went out on me this morning pretty bad. Looks like there will be a slight delay in this process. Color me frustrated.

NH Photo Shooter · 01-13-2016, 08:29 PM

OK, numerous Advil later and ignoring the pain, I installed the 36 pound spring. I noticed right away that it was much longer than the original (actually probably not original), and had more coils. The one that came in the gun had 17 I think, so it probably had been modified.

Once the new spring was in the gun I noticed a very significant difference. It is much stronger. So it probably will solve the problem completely. I will test tomorrow morning, assuming I can get out of bed. I've got my shooting kit stocked with a variety of 9mm ammo. I just hope my handloads will even cycle the action.

01-11-2016, 09:09 PM	#1
NH Photo Shooter User Join Date: Dec 2015 Posts: 18 Thanks: 17 Thanked 17 Times in 5 Posts	Extra step in chamber: Has anyone seen this before? I have a 1920 commercial with sear safety, likely made late 20's with likely modifications later. I've been shooting it quite a bit - fun pistol indeed. I was having way too many failures to feed, and have been working on that. The mags were hanging too low. The mag release showed no sign of excess wear, so I am assuming it was mismatched to the gun. Fixed that, and it helped. Got a Mec-Gar magazine, and that also helped. The other thing I noticed was that a fair number of rounds were feeding almost all the way, but the bolt stopped about a quarter of an inch from battery. Upon recent close examination of the chamber, I noticed an extra little step about that far back from the step that the case headspaces on. Not large, bit quite visible, and easy to feel with a sharp probe. Testing by manually inserting rounds into the chamber of the stripped gun, with the rounds angled as they would be in feeding from the mag, I could easily see this causing the problem I was having. I polished most of it out with 220 grit on a 3/8" dowel in a drill, going very slowly. It's not quite gone, but I definitely took the edge off. This also had the effect of polishing the chamber rather nicely, and possibly enlarging it by a very small amount. It's feeding much more reliably now. I have new springs on order from Wolff just in case a weak mainspring was contributing to the issue, but, really, I'm not dissatisfied with the reliability at this point: one or two minor failures (had to tap the toggle down) in over a hundred round test with mostly handloads. So what I wonder is, has anyone ever noticed this before? Bad chamber reaming, or was that little step there for some reason? I'm assuming careless machining, but wonder if anyone has had any similar experience. Thanks in advance for any thoughts.

01-11-2016, 10:34 PM	#2
Ron Wood Moderator 2010 LugerForum Patron Join Date: Jun 2002 Location: Santa Teresa New Mexico just outside of the West Texas town of El Paso Posts: 6,988 Thanks: 1,067 Thanked 5,099 Times in 1,676 Posts	The chamber step is a feature of the original design of the 9mm Parabellum, going back to 1903. It was included in 9mm P08s until 1940-41 when Mauser eliminated it, making the chamber in one machining step rather than two. The step was intended to act as a gas seal when the cartridge case expanded upon firing, keeping the greater part of the chamber free from powder fouling. Mauser eliminated the step primarily for two reasons, the introduction of steel cased ammunition and it made machining easier. Ron Attached Thumbnails Attached Images __________________ If it's made after 1918...it's a reproduction

01-11-2016, 10:40 PM	#3
mrerick Super Moderator - Patron LugerForum Life Patron Join Date: Dec 2009 Location: Eastern North Carolina, USA Posts: 3,900 Thanks: 1,372 Thanked 3,094 Times in 1,503 Posts	I am afraid that that the stepped chamber is part of the Parabellum's design. It's a desirable feature involved in helping achieve a more effective gas seal for the 9mm straight walled cartridge. It was expensive to manufacture, and later Lugers sometimes eliminated this feature. Hard to say what the result of your modifications will be... The cycling and cartridge feeding of a Luger is a achieved through a complex balancing act. The magazine is the first place to look when experiencing feeding problems. Replacement with a modern MecGar mag is a wise first step. Sometimes the wrong recoil spring has been installed in a Luger, which changes the cycle timing. While your 1920 commercial 9mm gun used a 18-19 coil recoil spring of medium pressure, later Mauser Lugers used one with 20-21 coils and more pressure. Sometimes Lugers can be ammo sensitive. Always use standard velocity 9mm 115gn or 124gn jacketed ammo. __________________ Igitur si vis pacem, para bellum - - Therefore if you want peace, prepare for war.

01-11-2016, 10:42 PM	#4
DonVoigt User Join Date: Apr 2015 Location: near Charlotte NC Posts: 4,678 Thanks: 1,441 Thanked 4,348 Times in 2,038 Posts	I do believe you said the magic words: "mostly hand loads". They were quite likely just a bid oversize and slightly belled perhaps, or at least the ones that didn't feed well. Polishing surely didn't hurt, except the chamber is no longer "original"; should that make any difference. __________________ 03man(Don Voigt); Luger student and collector. Looking for DWM side plate: 69 ; Dreyse 1907 pistol K.S. Gendarmerie

01-12-2016, 03:34 AM	#5
Sergio Natali User Join Date: Feb 2013 Location: Somewhere in Northern Italy Posts: 2,646 Thanks: 1,082 Thanked 1,783 Times in 1,007 Posts	Since here all P.08 are rebarreled many of them have been modified too, in fact I know that some people though that step was some sort of chamber fault. __________________ "Originality can't be restored and should be at the top of any collector's priority list.

01-12-2016, 08:02 AM	#6
NH Photo Shooter User Join Date: Dec 2015 Posts: 18 Thanks: 17 Thanked 17 Times in 5 Posts	Great information! Thank you all very much! It wasn't just the handloads that were exhibiting this phenomenon. Several brands of standard velocity commercial 115 and 124 grain ammo were doing this also. I also suspected that insufficient taper crimp might be at fault, but careful inspection and measurement with vernier calipers established that there were no dimensional differences in this area between my handloads and commercial ammo. So, it appears that I have compromised (not completely removed as yet) a factory "feature". Given the way I did it, I don't think I narrowed the chamber dimension at the end of the case. In order to prevent screwing up the headspacing, I mounted the 220 grit wet-or-dry on the dowel a bit back from the end, which was too large to pass into the throat. I also kept the whole arrangement moving a bit in and out. So I am guessing I partially turned the step into a taper, or maybe just took the hard edge off of it. I have to believe that polishing the chamber helped also. At any rate, the cases are not coming out any dirtier than they were before, and the gun feeds a lot better, both with handloads and commercial loads. Still, it's good to know that the issue wasn't being caused by crap machining, and I thank you guys again for the information. The next step is checking the mainspring against replacements from Wolff to see if that makes any difference. The spring set from them is literally "in the mail". I won't do any more after that, as the reliability as it is now is acceptable for a range-only gun, especially one that old.

01-12-2016, 08:32 AM	#7
mrerick Super Moderator - Patron LugerForum Life Patron Join Date: Dec 2009 Location: Eastern North Carolina, USA Posts: 3,900 Thanks: 1,372 Thanked 3,094 Times in 1,503 Posts	Glad that you have experienced improvement... Remember that the high precision and hand fit work involved with Luger manufacture made it a very expensive pistol at the time it was being manufactured. In fact, that is how Fritz Walther unseated the Luger with his P.38 (which cost less to make, and was double/single action). Marc __________________ Igitur si vis pacem, para bellum - - Therefore if you want peace, prepare for war.

01-12-2016, 09:01 AM	#8
alvin User Join Date: Jul 2007 Location: US Posts: 3,843 Thanks: 132 Thanked 729 Times in 438 Posts	Sounds like a marginal main spring issue. Replacing old spring with a new one should resolve the problem. Please keep us posted.

01-12-2016, 02:17 PM	#10
ithacaartist Twice a Lifer Lifetime Forum Patron Join Date: Mar 2011 Location: Atop the highest hill in Schuyler County NY Posts: 3,290 Thanks: 7,055 Thanked 2,483 Times in 1,324 Posts	[QUOTE=NH Photo Shooter;282895 I'm a bit frustrated with the Post Office. The Wolff spring kit was shipped Monday morning first thing by priority mail, and the tracking number didn't even show valid until this morning, and has shown no progress after arriving in Philadelphia. Should have had them Fedex it.[/QUOTE] I've been feeling your 'Postal Pain" for several weeks. I mailed a parcel containing $80 worth of Erma parts to a buyer in Iowa on the 15th of December. For the entire period, tracking said only that it had left my local P.O. I initiated a trace for it last week, which apparently dislodged it from wherever it was "stuck", and it was finally delivered today--2 days short of an entire month for its journey. __________________ "... Liberty is the seed and soil, the air and light, the dew and rain of progress, love and joy."-- Robert Greene Ingersoll 1894

01-12-2016, 02:33 PM	#11
Sergio Natali User Join Date: Feb 2013 Location: Somewhere in Northern Italy Posts: 2,646 Thanks: 1,082 Thanked 1,783 Times in 1,007 Posts	I see wherever we live we all feel more or less the same. Some days ago I ordered two Coltwood grips and I felt exactly like that waiting for the postman every morning. The funny thing is that as soon they were delivered I rushed like hell to put them on straight away! __________________ "Originality can't be restored and should be at the top of any collector's priority list.

01-12-2016, 02:41 PM	#12
rhuff Patron LugerForum Patron Join Date: Mar 2011 Location: Az. Posts: 2,273 Thanks: 2,692 Thanked 960 Times in 706 Posts	You may well find that a new, correct mainspring will solve your problem. As a spring undergoes compression and release, it will heat up somewhat, and if the spring in your Luger has reached the end of it's livelihood, it will begin to fatigue, and become less efficient. A Luger is such a balancing act of springs, mag, and ammo. Also check the feed ramps on the frame and barrel to be sure that they are smooth so as not to slow down the feeding cycle. Good luck!!

01-12-2016, 03:05 PM	#13
DonVoigt User Join Date: Apr 2015 Location: near Charlotte NC Posts: 4,678 Thanks: 1,441 Thanked 4,348 Times in 2,038 Posts	"I ordered the standard 36 pound spring and a 38 pound extra power one. I would hesitate to use the 38 pounder out of respect for the age of the gun." I believe you have it backwards, a stronger spring will save the old pistol from "battering" better than the weak one. A lighter spring would only be correct with lower power loads, JMHO. I'd go for the 40 lb! But just an observation- when I ordered a set of springs from wolf, 36-38-40, I fully expected them to be different numbers of coils and/or different wire guage and or different lengths. When they arrived, they were all the same wire guage, two were exactly the same length, and one was a little longer, but all had approx. 20 coils. The 36 and 40 were the same and the 38 longer. I have no way to measure the tension, but it is on my list to make something! It would be interesting to know what you get. You may have seen the chart attached; it seems the Germans could not decide which spring to use either! (Obviously they used a different method to determine the "poundage".) Attached Thumbnails __________________ 03man(Don Voigt); Luger student and collector. Looking for DWM side plate: 69 ; Dreyse 1907 pistol K.S. Gendarmerie

01-13-2016, 02:55 PM	#18
rhuff Patron LugerForum Patron Join Date: Mar 2011 Location: Az. Posts: 2,273 Thanks: 2,692 Thanked 960 Times in 706 Posts	During your "testing phases", I would do all of the testing with factory std. velocity 115-124gr FMJ ammo. Once you get the reliability to your satisfaction, then match your handloads to the factory ammo. I, also, handload for my lugers, but test only with factory ammo.....just a thought.

01-13-2016, 08:29 PM	#20
NH Photo Shooter User Join Date: Dec 2015 Posts: 18 Thanks: 17 Thanked 17 Times in 5 Posts	OK, numerous Advil later and ignoring the pain, I installed the 36 pound spring. I noticed right away that it was much longer than the original (actually probably not original), and had more coils. The one that came in the gun had 17 I think, so it probably had been modified. Once the new spring was in the gun I noticed a very significant difference. It is much stronger. So it probably will solve the problem completely. I will test tomorrow morning, assuming I can get out of bed. I've got my shooting kit stocked with a variety of 9mm ammo. I just hope my handloads will even cycle the action.