Alternative Artillery Barrel Fabrication

[sheepherder]

Originally Posted by TennBill2

I had planned to try and hand ream that last couple of thou. Do you think it's necessary to use the lathe with a piloted reamer? Bill

...???...As opposed to what other kind of finishing chambering reamer???

BTW: My very first post here turned into a 4-page thread on fabricating a 9mm arty barrel...

http://forum.lugerforum.com/showthread.php?t=21048

...Pretty much the same as this 30 cal arty barrel, except with a conventional Luger arty front sight & base (but still using the FN Mauser M24/30 rear sight)...

Edit: I was looking for a pic of the extension + reamer in use...but after reading my thread, I remembered I did this barrel differently...The headspace measurements I used and the method for finish reaming are detailed on pg 4 (I think)...I took all my final measurements with the receiver + barrel assembled, and the toggle assembly stripped...Then I figured out how much I needed to finish reaming and took the barrel back off and reamed it without the receiver in place...I used a full length resized 9mm case that I sized in my RCBS die set to ensure that I would be measuring the actual cartridges I would be shooting...And took all my measurements with that [dud] cartridge in place...My final headspace was .001" off my desired value...Good enough for gov't work...

[sheepherder]

Got a bit more done tonight...Cut the rear sight base dovetail, and the dovetail for the front sight blade...

[Thomas-J.]

I gotta say you got some mad skills, that is just too cool.

[sheepherder]

Originally Posted by TennBill2

Anxious to see how you finish reaming with the receiver on. I'm about at the same point, don't really want to spend $40 or so for a one off. Upside down 3/8 extension too big.

Then here we go!!!

First pic, we have the stripped toggle train installed with a dummy round in chamber. This is a 7.65 Luger round run through my RCBS die set (without expander). This is the ammunition I'll be shooting, so this is my baseline. I'm measuring the gap between the breechblock and the receiver.



I remove the dummy round and measure the gap again. (I have a rod inserted in the barrel to press toggle train back against the axle & take out any 'slack').



Removing the receiver, taking care not to crush the barrel.



Measuring the amount of the dummy round protruding from the chamber. I know it's too much because in the first pic the toggle is not fully closed.



I've figured out that I need to extend the chamber another .028" to give me .004" headspace (my target). .046" minus .022" is .024"...Add my target of .004" and I need to remove .028" to get my target headspace.



After reaming, I get .074"...This means I need to extend another .002" to hit my target of .004" headspace...



I'll re-install the receiver and hand ream the last .002"...



Here's that turned-down 6" 3/8" drive extension...



For all practical purposes, I'm done...But it's always good to double-check, so I've put my stripped toggle train back in place with the dummy cartridge, and put a 'headspace shim' between the breechblock face and the dummy cartridge...a .004" shim fits, and the breechblock remains closed and my .022" feeler is nice & snug...and .006" worth of shims gives me a loose feeler and a slightly raised toggle... finally, .005" worth of shims feels just right...

(My 'headspace shims' are just circles that I've punched out of plastic shim stock).



.005" is close enough to my target of .004". I'm easy.

There's dozens of ways to do what I just did, this is just one that I chose. YMMV

(Note: Any mistakes in math or spelling are my screwup. It's hard to machine, do math, and take pics at the same time)

Edit: BTW, I've done the headspacing now because I'll be machining the front sight blade in place, and the barrel won't fit into the headstock after that)...

[Neil Young]

Fantastic work--I believe that 90% of a machinist's skill is displayed by the machining sequence concept and the setup. This is of course more evident as the task complexity increases. You obviously have a high level of these skills. Anyone can learn to do a repetitive machining job on an assembly line, but the true measure of a craftsman is displayed on those one-of projects that are seldom, if ever repeated. Great job.!

Neil--an amature hobby machinist

[sheepherder]

The battery on my digi-cam pooped out while I was machining the front sight blade blank, so just imagine a small square of steel being milled & dovetailed...

And then pressed in the barrel dovetail...And then milling the sight assembly sides flat...



Front and rear sides milled flat...



Front sight squared off...



Milling the blade itself...Using a corner rounding end mill, just for S&G...



Front sight is roughed to shape; need to mount rear sight to determine blade height and finalize profile (it will be like the Finnish Luger profile...sorta)...



Hmmm...I'm running out of Allowed Images in my albums...I'll have to verbally describe what I'm doing from now on...)

[Vlim]

Just post the images straight into the thread, that should work

[sheepherder]

Originally Posted by Vlim

Just post the images straight into the thread, that should work

This forum only allows images to be added at the end of the post, and it will time out if the transfer takes more than 30 seconds...I'm on a dial-up, but I can post to another Forum (www.cncguns.com) and just post a link for anyone interested...

Thanks to all who were interested in this!

[SIGP2101]

Hi Postino that is amazing work. I like your solutions.

One Q. what method do you usually utilize to do 6 mm radius on the barrel flange. Do you do it on lathe or on the mill. How do you transit from taper into the radius.

[sheepherder]

Originally Posted by SIGP2101

One Q. what method do you usually utilize to do 6 mm radius on the barrel flange. Do you do it on lathe or on the mill. How do you transit from taper into the radius.

That's hard to answer, as this barrel does not transit from the radius to the taper...The sight base thingie is straight (in profile)...but to mill the radius on this one, I used the rotary indexing head...180º is rounded; the two sides are straight...and I used a 1/4" 4-flute ball end mill to mill it...

...But on a 4" or 6" barrel, I have a tool bit ground to a semi-circle, and turn the radius...

As for going from the radius to the taper...I just eyeball it...

[newluger]

Hi Postino,

Fantastic work and thank you for sharing with us. One question that I have,and I don't know if it has already been asked. Does the part need to be heat treated?

Peter

[sheepherder]

Originally Posted by newluger

Does the part need to be heat treated?

I really don't know...It's never been brought up in any of my gunsmithing books...(Wood, Nonte, Mitchell)...

None of the rifle barrels I've worked on over the years have been heat treated...Enfield, Mauser, Colt, Ruger...and AFAIK none of the pistols...Revolver or semi-auto...

This 'blank' is from Numrich...

I don't plan on doing any heat treatment...If you start out with good steel, heat treat shouldn't be necessary...IMHO...

[adowns]

I was about to ask how you cut the riflings in the barrel, but your last post says you used an MG barrel as your starting point. Is the twist rate compatable?

[John Sabato]

Heat treating of the barrel steel is not required. Rich, the next time you do a front sight base please do a video of the machining process. For production of luger barrels I would think that an EDM process would be the simplest method to achieve the front sight base and muzzle ring profile but for one barrel at a time as you do them your methodology makes perfect sense. I also think that your method of creating the sight base AFTER the barrel is installed & headspaced results in a perfect vertical alignment with the rear sight! Absolute genius IMHO!

If you end up hosting your photos over on CNCguns remember that you can surround the URL for the photos with IMG and /IMG tags in square brackets [ ] and the image will appear in your post. I am not able to increase your photo gallery space but perhaps the ADMIN might be able to do that. Keep up the great work.

P.S. Make a second barrel & sell it and use the money to get you a broadband internet connection!

[sheepherder]

Originally Posted by adowns

I was about to ask how you cut the riflings in the barrel, but your last post says you used an MG barrel as your starting point. Is the twist rate compatable?

Sorry; wrong blank! My bad! I used the 30 cal MG barrel blank in another project [Broomhandle Mauser]. This was a 1 3/16" dia no-name blank from Numrich.

I'm not too fussy about twist; I reload, and tailor my loads to the individual weapon being used, for these special one-off projects. Pretty much whatever is available is 'good enough' for me.

Originally Posted by John Sabato

Heat treating of the barrel steel is not required. Rich, the next time you do a front sight base please do a video of the machining process.

Difficult to shoot pics and machine at the same time...and video would probably take longer than my digi-cam memory chip would allow...

Absolute genius IMHO!

"Dummies In Action!" was our motto at Kimberly-Clark...

If you end up hosting your photos over on CNCguns...

I can stash the pics on PhotoBucket & link them; I owe the guys at CNCGuns a thread like this one...but I can do two; not a biggie...

P.S. Make a second barrel & sell it and use the money to get you a broadband internet connection!

It's a long story, but my heavily wooded rural area does not have broadband support.

[John Sabato]

You can get broadband via satellite (e.g. Hughesnet)... in areas where cable or DSL are not available.

[sheepherder]

Originally Posted by John Sabato

You can get broadband via satellite (e.g. Hughesnet)... in areas where cable or DSL are not available.

Short answer is no...County-owned trees in the way; only sats available are low [35º] on the horizon; and I am in the area known as "The Snow Belt"...

There are other issues with cable & DSL, but suffice it to say, broadband in my area is not practical...

[Vlim]

Otherwise just send an email and we'll post them for you.

[sheepherder]

Got a bit done on the rear sight base today...Roughed it out; cut the dovetails; milled the ramp...I'm not entirely happy with it...I made a mistake with the axle hole, and the whole base ended up too high for my taste...(all your base are belong to us)...

Sight blade is not cut down yet; just looking at how it fits...

[John Sabato]

Mount the dish on a tower attached to your chimney to get it above the trees...