Data on Luger barrel thread specifications

[tankcmdr]

Hi:
Does anyone happen to know what the thread specifications are for the P08 barrel? Thanks.

tankcmdr

[Norme]

Hi Cal,
Welcome to the forum! I don't know the thread specifications for the Luger barrel but I can tell you that they were all Whitworth thread, as were the grip screws.
Good luck, Norm
https://en.wikipedia.org/wiki/Britis...dard_Whitworth

[G.T.]

Hi Tankcmdr, and welcome to the forum again! The thread is as follows
.710 X 20 TPI at 55 degree...…. AND NO! you can't use 60 degree tooling, it will stop about 1/2 of the way, and sometimes stop forever! ........How do I know this you might ask? Very stubborn people like me just cannot resist the temptation? Therefore, I come by the experience honestly... so, again, 55 degree, no more no less.... Best to you, til...lat'r...GT

[DonVoigt]

It is a 55 degree thread as noted by Luger doc, but "specs" are a combination of metric and English;
18mm x 20 TPI.

I have a little different opinion than GT on 55 vs 60 degree compatibility; I've cut many 60 degree threads and threaded them into original 55 degree receivers.

Each receiver is different and "real" luger barrels from the day will not necessarily interchange into "real" luger receivers.

I find that when I grind the angle on my own thread cutting bit, I'm not good enough to tell 55 from 60 degrees!
Cutting the thread just a bit deeper will allow the barrel to screw into the receiver; the draw at the flange is what keeps the barrel nice an tight anyway. JMHO.

[Norme]

Hi Don,
"What keeps the barrels nice and tight" is the rifling's right hand twist. If anything repeated firing will slightly over tighten the barrel causing the front sight to move left and the gun to shoot right. That is the reason military Lugers had the famous "witness mark" stamped below the barrel.
Norm

[tankcmdr]

Thanks for the response. I'm considering machining some match barrels in 7.65 and 9mm Parabellum for this action. Tankcmdr.

[DonVoigt]

Originally Posted by tankcmdr

Thanks for the response. I'm considering machining some match barrels in 7.65 and 9mm Parabellum for this action. Tankcmdr.

Match barrels?
What profile?

Be careful not to make them so heavy that they won't cycle the recoil action of the luger.

[DonVoigt]

Originally Posted by Norme

Hi Don,
"What keeps the barrels nice and tight" is the rifling's right hand twist. If anything repeated firing will slightly over tighten the barrel causing the front sight to move left and the gun to shoot right. That is the reason military Lugers had the famous "witness mark" stamped below the barrel.
Norm

That is the first time I've heard that explanation of the existance of the witness mark. Do you have a reference for that tidbit of information?

[briskspirit]

Originally Posted by Norme

Hi Don,
"What keeps the barrels nice and tight" is the rifling's right hand twist. If anything repeated firing will slightly over tighten the barrel causing the front sight to move left and the gun to shoot right. That is the reason military Lugers had the famous "witness mark" stamped below the barrel.
Norm

Is this witness mark available only on military lugers? Because I have it on my M1906 commercial too.

[Norme]

Hi Igor,
My answer to your question is that, since I only collect German military Lugers, I really don't know. I do know that Kreighoff never used witness marks and that late in 1942 Mauser finally dispensed with them as well.
Norm

[Norme]

Hi Don,
My statement is based on observation, the "witness marks" on military Lugers that have seen a lot of use frequently indicate some over tightening. Also since the only other such marking on military Lugers is on the front sight it seems like the most logical explanation. If you can come up with a more rational explanation i'd like to hear it.
Regards, Norm

[G.T.]

Having re-barreled & barreled a considerable number of P.08's I have a totally un proven theory on what the witness marks do, and what they mean?
One thing I found interesting, is that no mater where the barrel witness mark is or ends up, the mark on the receiver is always dead center on the receiver bottom? Ok, no big surprise except it means that the initial receiver mark and the barrel marking may have been applied at different times.. Ok again, why? Why not just screw the barrel on and nail it with a mark and say finished? Well, I think that is what they wanted to do, but the real world accuracy boogieman just wouldn't let them off that easy...
My theory is the receiver comes with the witness mark, the barrel is screwed in and it is mechanically set to zero, then it is witness marked making a new mark on the barrel in concert with the existing mark on the receiver. The barreled receiver goes on it's merry way thru production right up to the very end, where it was dynamically fired to establish real zero and the barrel was slightly adjusted, or not, to obtain what they considered acceptable accuracy... As a result, it may have been right on, explaining weapons that show perfect alignment, or slightly off for weapons that required adjustment? What else could it be that they would disturb accurate existing alignment marks? Just my theory.. best to all, til...lat'r....GT
BTW, Normes theory is relevant as well, makes sense, although I've not had any barrels migrate on me yet, but, still wondering, what other reasons could there be?
BTW Squared! It also seems that they did the final barrel correction outlined above, I suspect, in order to keep the front sight centered and indexed. So when it arrives in the field, it can be drifted both ways equally, for each unique shooters needs if necessary? Almost all nice P.08s I have seen, are dead center on the front sight base and blade??

[sheepherder]

Originally Posted by DonVoigt

I find that when I grind the angle on my own thread cutting bit, I'm not good enough to tell 55 from 60 degrees!

Me either! I use my center gauge to grind my lathe bits. The usual one is 60 degrees, but you can get the 55 degrees too.

[DonVoigt]

Originally Posted by Norme

Hi Don,
My statement is based on observation, the "witness marks" on military Lugers that have seen a lot of use frequently indicate some over tightening. Also since the only other such marking on military Lugers is on the front sight it seems like the most logical explanation. If you can come up with a more rational explanation i'd like to hear it.
Regards, Norm

There has been much discussion on witness markings and no conclusion that I recall.

They make some sense if one wanted to remove and re-install a barrel.

Many witness markings do not align, neither were they struck at the same time with the same instrument on the flange and receiver.

Some years back Dwight Gruber was doing a detailed study of the witness marks and what they might indicate, and when they were applied.

I believe that in this case logic has little to do with the presence or absence of the witness mark.

With some 40-50 ft lbs of torque applied to seat the barrel,
I do not subscribe to the rotational torque from firing being able to "tighten" the barrel though.

And what about the witness marks that don't align the other way?

A puzzle for sure!

Maybe Dwight will chime in with his idea or conclusion.

[DonVoigt]

Originally Posted by sheepherder

Me either! I use my center gauge to grind my lathe bits. The usual one is 60 degrees, but you can get the 55 degrees too.

Yes,
I use my 60 degree template and just go a little more pointy!

If you have a spare 55 degree tool, please send it to me.

[tankcmdr]

Originally Posted by DonVoigt

Match barrels?
What profile?

Be careful not to make them so heavy that they won't cycle the recoil action of the luger.

I'm not sure if that will be a concern:
https://www.icollector.com/Custom-Ge...NGxCD3aWgczcbU

[sheepherder]

Originally Posted by tankcmdr

I'm not sure if that will be a concern:
https://www.icollector.com/Custom-Ge...NGxCD3aWgczcbU

Interesting 'shoe' that the Bo-Mar rear sight is mounted in. It fastens to the rear toggle but differently from others I've seen. I am certain I have never seen this sight mount before.


Doesn't really solve the problem of the rear sight slapping around under recoil. But an interesting alternative to the more common rear toggle mount.

[Norme]

Hi Don,
I can think of no reason why anyone, particularly a military armorer, would need to remove a barrel and then reinstall that same barrel back on that same gun. Can you?
Norm

[DonVoigt]

Originally Posted by Norme

Hi Don,
I can think of no reason why anyone, particularly a military armorer, would need to remove a barrel and then reinstall that same barrel back on that same gun. Can you?
Norm

No.
But it is the only reason I can think of to apply a "witness" mark!