Artillery Barrel Specs???

[sheepherder]

Continuing on my never-ending quest to get a long barrel on my commercial P-08...

Clockwise from top left - I decided to shorten the FN Mauser M24/30 rear sight to more the length of the LP-08 Luger...Milled 3/8" off the front; cut the slots with a keyway cutter; milled the front to 3/8" width for my sight base; the completed shortened sight leaf/slider compared to an unmodified C96 sight; my rounded muzzle; the tool bits used for the taper and the muzzle contouring; and in the center, how the barrel looks now.

My grinding wheel didn't have a very good round corner, so I had to do a bit of filing/sanding to get the muzzle to look rounded...and I had to mill off a couple sight leaf numbers so the leaf wouldn't look too odd...also the sight base had to be recontoured so the shortened sight would slip in and be capable of elevating...

I'm trying to locate a receiver/barrel extension/slide (choose one) so I don't have to give up my 30 cal barrel...I'll make a couple calls tomorrow and see if I can scrape one up...

[Vlim]

Nice work! Keep these posts coming!

[sheepherder]

OK, I think I can scare up a few more pics...

I pulled the 30 cal barrel off my "shooter" (1st pic) and screwed my faux-artillery barrel in (2nd pic)...without any torqueing, it's about 1/2 a turn off...or about .025"...(see gap in 3rd pic)...

I assembled it on the frame so I could get an idea of what it is I'm doing...

If I use 1/8 turn as my "crush" factor, then I need to remove ~.018" from my flange...which would put me at about .152" for my flange thickness...and Rick W. gave me a measurement of .135" on his artillery barrel...that'd make it ~.017" off...close enough!!!

[sheepherder]

Well, it definitely looks different...

I haven't cut the notch in the chamber yet, so I couldn't close the breech...

Now that I've gotten this far...I'm not sure I like it...

Hmph...My rear sight looks awful high, doesn't it???

Drat!!! I'll have to make another base...lower...

Maybe I should just screw my old 5" barrel on...

[sheepherder]

Originally Posted by Rick W.

The extractor slot measurement for twisting on a Luger barrel is just another reference in use, every one has their own methods.

FWIW

Sounds good to me!

[sheepherder]

Originally Posted by Jack Lawman

I do have one question... How do you index the barrel so when you screw it on the frame the sights are not canted?

Jack

OK, Jack, I finally got around to answering your question...

Here's the receiver snugged up to my Rube Goldberg artillery barrel. Threads cleaned off and a dab of grease applied. Tightened three times, snugly. It's about 1/2 turn off. (1st pic)

Here's the barrel and the receiver leveled as they would be when assembled. A .025" feeler gauge fits between flange and receiver, all around. (2nd pic)

Here we have the barrel set up in the lathe to cut the flange back .022"...That'll give me .003" of "crush"...which is approximately what I figured out that an ejector width is...(3rd & 4th pics)

[sheepherder]

Cutting the flange back means I also need to cut back the overall length of the threaded stub...my 30 cal barrel was .755", so that's what I'm shooting for here...(1st pic)

I didn't bother taking more pics of the same procedure...suffice it to say that I cut back the flange and stub 4 times to get them spot on...here's the final result, both receiver and barrel level when assembled, without pulling the threads out of the receiver...(ignore the penny loafers - they're my machining shoes)...(2nd and 3rd pics)

Here we are, properly (well, properly for me!) indexed, torqued, and assembled. Ejector notch and feed ramp still needs to be cut. After those two are done, I'll finish cut the chamber and set the headspace. (4th pic)

[sheepherder]

I used a cutoff tool bit to do my flange and stub nibbling. I've found I get better control over very small increments than with a "proper" cutting bit. Just one of my many eccentricities.

I've also acquired a wrench and barrel vise from a member on ARFCOM who got them on eBay. They work pretty well, with a couple modifications. My old barrel pulling/installing tools were pretty crude...

I make sure I have a squib rod in the barrel when tightening the barrel vise down (not shown in pics).

Edit: The brass thingy in the chamber is a mandrel for holding the breech so I can turn it concentric with the bore/chamber. It's cut the same taper as a Parabellum cartridge.

[Ice]

This is just plain, flat awesome! I wish I had the talent/training to do something fine like this but its too late for me. At least I can enjoy and wonder at that which others create. Thank you very much for taking the time to post the pics and explanations of your work.

One question though. I probably missed it but is the barrel pre-rifled or are you planning to rifle it?

Charlie

[sheepherder]

Originally Posted by Ice

One question though. I probably missed it but is the barrel pre-rifled or are you planning to rifle it?

It's a rifled "barrel blank" from Numrich/Gun Parts Corp. I got the blank many years ago, but they still have them. They just cost more now...

[Jack Lawman]

Originally Posted by postino

OK, Jack, I finally got around to answering your question...

Thanks for taking the time to illustrate your answer. The only thing better than this thread would be to stand next to you and watch you do it.

Keep up the fine work!

Jack

[G.T.]

I have learned a bunch in this thread.... Not just about technique, but about free thinking... Great effort on a neat project... I tip my hat... Best to all, til...lat'r...GT

[sheepherder]

Originally Posted by G.T.

I have learned a bunch in this thread...

Me, too! I've owned two Lugers in the past (some 20 yrs ago!), and swapped barrels on them, but there's been a lot of tips here that I'd either forgotten or never knew. Keep 'em coming!

Not just about technique, but about free thinking...

I dunno 'bout that...I'm pretty set in my ways...I like to add new methods and tools to my lineup (like that barrel wrench/vise), but I learned most of my mechanical "skills" back in the late '60's/early '70's...Before numerical or computer controlled machinery...I wish I had the time to learn CNC (and had the $$$ to own a CNC workstation), but I think I can make do with what I've got...

[Jack Lawman]

Originally Posted by postino

...but I think I can make do with what I've got...

Have you seen the movie "IronMan" with Robert Downey?

http://en.wikipedia.org/wiki/Iron_Man_(film)

If you haven't, treat yourself... you should see what he pulls off in a Taliban cave!

Jack

[sheepherder]

Got a bit more done today...

1st pic shows milling the ejector notch with a Woodruff keyway cutter. I used two, one 1/8" and one 3/32". I can't find whatever it was I used to use, so these two plus a bit of filing are what I gots.

2nd and 3rd pics show the barrel w/notch installed.

[sheepherder]

1st pic here is reaming the chamber for 9mm Parabellum, with a Clymer finishing chamber reamer and floating reamer holder. I've determined that I only need to cut another .018" to get my desired headspace. Clymer recommends high-Sulphur content cutting oil; 1/32" cut at a time; chips blown out between cuts.

2nd pic shows the reamer fully inserted; final cut.

3rd pic is barrel back on receiver w/notch cut and chamber finished. Fully assembled, almost ready to shoot...

...but the barrel still needs the feed ramp milled...

I could shoot it one shot at a time...and stick the cartridges in by hand...but I can wait...

Edit: Pics updated to show how it *should* have been done, rather than the clumsy way I did it.

[sheepherder]

I just know that someone is going to ask how I figured out the correct amount to remove for my desired headspace...or why I reamed a chamber back in the initial stages...

It's because the way this pistol is constructed, headspacing a partially reamed chamber is pretty simple...at least, it is the way I do it...

First I strip the breechblock of ejector and firing pin. 1st pic shows stripped breechblock/toggle assembly, axle pin, squib rod, and barreled receiver.

2nd pic shows assembled breechblock/toggle/axle pin assembly mounted in barreled receiver, with the squib rod applying light pressure against the breech face. (You can just see the rod in the chamber and at the muzzle).

3rd pic shows measuring the gap between the receiver and the breechblock with a feeler gauge (still with light pressure on squib rod). It's .035" on this assembly.

4th pic shows a sized cartridge [.754" OAL max] inserted in the partially chambered barrel, and the toggle assembly pressing against the cartridge. The gap between receiver and breech is measured again (with feeler gauges), and the difference between this and the previous measurement, plus the amount of headspace desired, is the amount to be reamed with the Clymer finishing chamber reamer. In this case, it was .018".

With the barrel again removed from the receiver, I just measured the length of the chamber (from where the cartridge mouth locates) to the chamber rim, chucked it up in the lathe, and reamed it down the required .018".

To avoid discussion, I didn't specify what headspace I used here, because this is a commercial model, and whether it's headspace is different from the military model or not, I like a tighter headspace than what I usually find on production pistols.

Rube Goldberg Lives!!!

Edit: Thanks to Rick W for noticing the goof in the amount of material to be removed.

[sheepherder]

I'm cutting the feed ramp now...

1st pic - I center the [stripped] barreled action in the mill vise, and set it to what I think is the desired angle...

2nd pic - I've eyeballed an old P-08 9mm barrel throat, and made my cut with a 3/8" end mill...here's the result...

3rd pic - Barreled action has been reassembled and weapon is fully functional once more ...Sharp chamber edges still need to be smoothed out; tool marks on outside of front barrel band, rear sight 'sleeve', and rear sight base need to be draw filed or sanded, and the rear sight itself needs some more work...but it should feed and fire now...

I'll reload some dummy rounds (no powder/primer) and see how it cycles...Might have to adjust the feed ramp angle...

...But in one of those annoying occasions, I can't find my 9mm shell holder... I'll have to get up to the local sporting goods shop and get another one...

I have 5 or 6 hundred 9mm rounds reloaded, but they're loaded hot for my S&W 659...I don't want to chance blowing the ejector through the breechblock, so I'll wait and load some light rounds to try this booger out...

[sheepherder]

BTW: I'd like to thank the owners and moderators of this forum for hosting this brief "HowTo". I understand that this is a Collector's Forum for P-08 Lugers, and that many would consider this type of modification to be blasphemy...

So a big "Thank You!" to all of you!

(And if anyone ever finds a copy of the LP-08 specs/blueprint, I sure would like a copy!)

[Lugerdoc]

Just remember that the front sight base is higher on LOP8 barrels than on the PO8 because of the higher rear sight. TH