Artillery Barrel Specs???

[sheepherder]

...fourth pic showing some of the chips while chambering; fifth pic shows a re-sized 9mm shell in the new chamber; sixth pic is what we have now...

The rear sight base has been contoured at rear; rear sight base is ~1/10" longer than Luger because I'll be using a shortened Mauser C96 tangent rear sight. Front sight dovetail is 5/16"; smallest I could find, which means my front sight will be fabricated in place. Muzzle and breech have been turned down slightly. Breech (where thread is) is still about 1/8" longer than needed, and thread diameter is still a bit oversize. Chamber will be cut deeper and headspace reamed in when breech is cut to length and barrel is fit to receiver.

I'll start on the front sight blank and rear sight base next.

[sheepherder]

Got some work done on the rear sight base today...Cut the reverse dovetails; made sure it would be a tight fit; and hogged out the sight cavity...

[sheepherder]

...and cut the slot for the C96 Mauser rear sight axle with a keyway cutter...Fits real good!

Need to locate the axle pivot holes and then mill the "slope" for the slider...I was thinking of shortening the C96 sight, but I think I'll leave it as is...If I have to, I'll mill a crescent in the bottom of the leaf to fit snug over the receiver (instead of notching the receiver)...

Heh...A 1000 meter Luger sight...

[John Sabato]

The barrel length is normally measured as the distance from the end of the muzzle to the front of the breechblock face. Slip a cleaning rod into the assembled gun, mark where it stops and then measure the rod ...

From the photos you have provided (Great photos of the process, BTW)... it looks like your front sight is going to have to be pretty darn tall!

[sheepherder]

Originally Posted by John Sabato

From the photos you have provided...it looks like your front sight is going to have to be pretty darn tall!

By sticking my squib rod in the bore, I measure .635" from the top of the rod to the top of the sight leaf...I'll make my front sight the same height...

I don't know how tall the LP08 front sight is...but this will look sort of right...

[Ingvarg]

Impressive !!

Great work and thanks for shering.
I,ve got a good old Meuser lathe but not a milling machine so all I can do for now are straight barrels without sight ramps etc.

[sheepherder]

Originally Posted by Rick W.

Sorry about the typo, 200mm is about 7 7/8" as you did you 25.4 trick. I bet I measured on my foot ruler from the "1" to try to be accurate...

Good. I wanted to make sure I wasn't an inch short.

I was measuring from the breech face as well. It'll be within a sixteenth.

It has been a while since someone read one of my posts for technical content...

I printed out your dimensions...It took me this long to realize the OAL was an inch off...

[John Sabato]

Ingvar,

You should still be able to do barrel tapers by simply offsetting your tailstock on the lathe by half the difference between the large end and small end of the taper!

May I recommend two websites that you may find of great interest?

http://bbs.homeshopmachinist.net/index.php

and

http://www.practicalmachinist.com/vb/index.php

There are some really great tips and machining discussions on these two websites...

[sheepherder]

Originally Posted by John Sabato

You should still be able to do barrel tapers by simply offsetting your tailstock on the lathe by have the difference between the large end and small end of the taper!

I hate having to re-center my tailstock afterward...

I cut my tapers with the tool post (compound rest)...If you look in the top pic of post #34 above, you'll see the handle of the tool post feed sticking out the right side...

I set the tool post up and use a dial indicator against the part of the barrel to be tapered to show the amount of taper...in this case, it was ~.080"; so I swiveled the tool post until the dial indicated .040" of taper...Locked 'er down, and started cutting/feeding (manually)...

BTW: This is the machine I use for all this...


3-In-1 Multipurpose Machine with Micro Feed

[sheepherder]

...???...Did I miss something???...

Posts come and go...

Oh, well...If anyone has any constructive criticism, please post away!!!

I roughed out a front sight blank today...It's installed, but I need to get some new belts for the lathe...The 5 year old 3/8" belts are delaminating...(I was wondering what that strange thumping noise was)...

I'll see if I can find some today and then re-mount my rotary indexing head again and finish milling the barrel flange to size; the same with the front barrel band; and then start in on the front sight...

[John Sabato]

Hmmm... Rick, just curious...why did you delete your post?

[Jack Lawman]

Originally Posted by postino

Oh, well...If anyone has any constructive criticism, please post away!!!

I don't have anything constructive to offer, but I will say that I very much enjoyed following your progress. I one day hope to acquire some machinist skills.

Looks like you did a professional job with what appears to be a hobbyist's machine. I'm good friends with an old school machinist. His lament is that it's a dying art. CNC is king these days.

Again, thanks for taking the time to share... I'll bet more people than you realize are enjoying this thread.

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

[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 -

I left the flange a bit oversize. The most a Luger barrel can be off is .050"...(20 threads per inch = .050" x 20). I read in another thread here that 1/8 of a turn is about right for torqueing the barrel down. So the most the barrel can be off is 7/8 of a turn... or .044"...

My flange is at .170"...Rick W quoted me .135" for the flange on his artillery barrel...So I have .035" to play with...I'll screw the barrel on and torque it down three times, then figure out how much I need to thin the flange from there...(It's easier to do than describe)...

I'll take pics...Right now, I'm still milling the front sight to size...I've mounted my barrel in my rotary indexing head and milled the front sight band and flange down, 4�º at a time...and milled the front & sides of the front sight flat with the barrel base...

This barrel is easier than most I've done...It has a convenient flat (rear sight base) for spirit leveling...that's what I'll use to level the barrel in the receiver.

[sheepherder]

Originally Posted by Rick W.

Lots of setups and just flat work in this project, takes a lot of time and planning.

I've been on vacation this week...

I liked the comment on the spirit level; a little something for me to ponder..

I found a nice little [3"] aluminum one at Home Depot...

Got the front sight roughed out...more...It won't look exactly like a Luger front sight; no way I can do micro-machining like that...which is why I mounted my sight before machining...

So, I roughed it to shape, milled the sides at an angle, made a crude arc to the leading edge...I made the height the same as the rear sight leaf top...It's too tall, but I'll have to think a bit as to how high to make it...

[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.

[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...