Artillery Barrel Specs???

[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.