Gunsmithing Too short for headstock

[bsalbrig]

I’m trying to chamber my first barrel and my small lathe for some reason isn’t picking up on threads so I want to use my larger one. The problem with the larger one is the barrel isn’t long enough to get through the headstock. I’m considering attaching some tube to the end of the barrel to give an arm to use to push the barrel to get it aligned. I want to leave the barrel as long as I can when done. I’ve considered welding an open tube to the end or fitting some bushings in a tube to extend it. It’s about 4” short. I have some 12” ground tungsten rods that fit perfectly to the bore so I can figure out which way the barrel is curved.
Im wanting to use a tube so I can use the rods.

Is welding a crazy idea? I’ve read the end of the barrel has to be cut off because of damage from lapping so the welded tip will be removed. When I do the crown I can either thread a tube or just leave the action on to get enough length.

 

[Easy_E]

If your going to cut the end off just thread it for an extension . Old barrels and barrel cutoffs are great for this internal thread to 5/8-24 and thread it on . Another trick if you lathe bore is large enough is drill a hole tight to you barrel OD and tap a couple set screws to hold the extension on.

PS on the action side the same just thread a large tube inside the same as your action threads so the muzzle hangs out enough to crown / thread.

 

[bsalbrig]

If your going to cut the end off just thread it for an extension . Old barrels and barrel cutoffs are great for this internal thread to 5/8-24 and thread it on . Another trick if you lathe bore is large enough is drill a hole tight to you barrel OD and tap a couple set screws to hold the extension on.

PS on the action side the same just thread a large tube inside the same as your action threads so the muzzle hangs out enough to crown / thread.

Thanks
It’s going to be my first time attempting a barrel and I just wanted to see if I was way off base in my thinking about this. I’ve been working on my setup over the last couple of months. I’ve got the threading down. I’m using an internal boring bar off the back side so I thread away from the ledge…. The relief angle shim being the wrong direction tricked me for a bit but I figured out the problem and now am getting perfect threads.
I also want to use the big lathe because it’s essentially new and is far stiffer than the small one.
The lathe is a monarch weiler 517. It has a 2” bore.

When I do get started it will be the first chamber I’ve reamed. I’ve practiced on all the other operations but I don’t see how to practice reaming other than just doing it. I’m doing 6br.

 

[lariat]

Thanks
It’s going to be my first time attempting a barrel and I just wanted to see if I was way off base in my thinking about this. I’ve been working on my setup over the last couple of months. I’ve got the threading down. I’m using an internal boring bar off the back side so I thread away from the ledge…. The relief angle shim being the wrong direction tricked me for a bit but I figured out the problem and now am getting perfect threads.
I also want to use the big lathe because it’s essentially new and is far stiffer than the small one.
The lathe is a monarch weiler 517. It has a 2” bore.

When I do get started it will be the first chamber I’ve reamed. I’ve practiced on all the other operations but I don’t see how to practice reaming other than just doing it. I’m doing 6br.

You could try reaming with a piece of scrap stock just to get the feel of it. A couple of tries won’t hurt the reamer. If it does either you have something wrong or the reamer is not quality. If you have something wrong its better to ruin the reamer and not the barrel.

 

[Easy_E]

Thanks
It’s going to be my first time attempting a barrel and I just wanted to see if I was way off base in my thinking about this. I’ve been working on my setup over the last couple of months. I’ve got the threading down. I’m using an internal boring bar off the back side so I thread away from the ledge…. The relief angle shim being the wrong direction tricked me for a bit but I figured out the problem and now am getting perfect threads.
I also want to use the big lathe because it’s essentially new and is far stiffer than the small one.
The lathe is a monarch weiler 517. It has a 2” bore.

When I do get started it will be the first chamber I’ve reamed. I’ve practiced on all the other operations but I don’t see how to practice reaming other than just doing it. I’m doing 6br.

If you figured all that out chambering should be easy for you . I started out on some cheap green mountain blanks first and still shoot a 7 twist 22-250 I built .
I believe bsalbrig was saying there are other ways to thread short barrels like between centers or with a steady rest .

 

[bsalbrig]

If you figured all that out chambering should be easy for you . I started out on some cheap green mountain blanks first and still shoot a 7 twist 22-250 I built .
I believe bsalbrig was saying there are other ways to thread short barrels like between centers or with a steady rest .

You could try reaming with a piece of scrap stock just to get the feel of it. A couple of tries won’t hurt the reamer. If it does either you have something wrong or the reamer is not quality. If you have something wrong its better to ruin the reamer and not the barrel.

I got a Manson reamer and it looks very nicely ground but I just got the finish and not the roughing reamer. Guess it’s not too hard to bore a .237 hole to test my process. At least 6br is short.

 

[bsalbrig]

If you figured all that out chambering should be easy for you . I started out on some cheap green mountain blanks first and still shoot a 7 twist 22-250 I built .
I believe bsalbrig was saying there are other ways to thread short barrels like between centers or with a steady rest .

I think what I’m doing is unique with the internal boring bar off the back side of the part in reverse. I saw the guy on YouTube running upside down and though this would be a better way since I would be able to see the insert and it would hold the cutting oil better.

I’m using the 3/4 model here

ISCAR STYLE I.D. THREADING TOOL HOLDER

THIS TOOL PRODUCES CLEAN, BEAUTIFUL THREADS WHEN USED WITH OUR 16IR AG60 INSERTS. CLICK "SIZE" MENU TO SELECT SHANK SIZE. RH INTERNAL THREADING BAR ACCEPTS INDUSTRY STANDARD 16IR AG60 INSERTS INSERTS PURCHASED SEPARATELY

latheinserts.com

But I’m using an external profile 16EL-16UN insert. I was getting micro cracks on my thread surface that I discovered was because the shim is tilted towards the end of the tool but needed to be tilted back. It was causing the side of insert to rub on the threads while cutting. I made some stainless shims and cut them to the proper angle now my threads look flawless.

 

[bsalbrig]

Serious question....



How much is that bore deflecting in the first few inches that you need to correct for it....relative to just chucking up the barrel in a 4 jaw and indicating off the lands and grooves?

Is it an actual significant amount? or is it just some OCD shit?


I'm genuinely curious, have you indicated a barrel off the lands and grooves, then inserted a ground rod and measured a considerable difference?

I mean, maybe ive just gotten lucky, but I've never went through that effort to chamber a barrel and I've never had a problem

Maybe it’s not necessary but if there something to gain by lining up the bore I’d rather put in the effort to do it the best way possible. I’ve done some recrowns and only centered the bore and the guns shot well.
I’m getting real close to doing the barrel. I’ve got to do some test ream pieces first though.

 

[bsalbrig]

I did the barrel and it turned out good enough. The stainless from the barrel was much softer than the 304 I was using as a test piece. I decided I don’t yet have the skill to time the curve upwards so I let it headspace where it first fell. I’ll try with the next to time it.

My plan for the next barrel is to use an indicator mounted to my cross slide and zeroed off on the reamer holder then move the cross slide in the depth of the chamber. I should be able to use my dro for setting depth if I do that.

 

[hero's machine]

A viper style action jig would hold a short barrel if you're not greedy with the feeds.

I'd skip measuring off of stuff unless the stuff is the barrel. Grab a long reach stylus and rock on.

 

[MarinePMI]

Set up between centers, and use a drive plate and lathe dog to drive the barrel, with a center rest set up to hold the barrel, so the tailstock can be removed and the barrel can be threaded and chambered. It's how they used to do it back when most home lathes didn't have a big enough spindle bore to allow the barrel to be set up through the headstock. Ask anyone that learned how to chamber barrels on an old Atlas or Craftsman lathe...

I used to have a picture from 20+ years ago, of me doing exactly this.

Lots of different ways to skin this cat...

 

[MarinePMI]

Took me a few minutes to find a few. Now, bear in mind, there's a dead center in the headstock, and a live center in the tailstock to set up the barrel "between centers". This assures the barrel is aligned along the axis of the bore. The steady rest is then put in place to support the breech end of the barrel, so it can be threaded and chambered.

And don't laugh, these photos are 20+ years old...I was a lot younger (and thinner) back then

Preparing to cut tennon threads on a tapered octagonal barrel destined for a Martini Cadet action.

Chambering a different barrel (.17 caliber). Notice the bolts in the drive plate. They hold the piece of plywood up against the lathe dog, keeping the barrel from coming off the dead center.

It wasn't elegant, but it worked, and always cut a true and concentric chamber. Lathe was in back gear at 55rpms, and the reamer was held with a small lathe dog, and fed in by hand, with the tailstock live center supporting the rear of the reamer (if you've ever wondered why reamers have a divot in the rear?).

It's slow and tedious (constantly pulling the reamer out, brushing off chips, dipping in cutting fluid, and then making the next cut, feeling the reamer load up with chips, and repeating the process). But it's a way to cut an absolutely clean and accurate chamber. When you have to get something done, you work with what you've got.

 

[hero's machine]

If you dig around you'll find Les Brooks documenting building a rifle on a 7x12" lathe on the tail gate of his pickup while living in a motor home. He was an instructor at Trinidad state and quite talented. He did some impressive stuff with very little.

 

[bsalbrig]

I’ve now done 3 barrels and one of them a second time and I’ve learned from each. The first I did I indicated each end to center through the headstock…. Pretty much the between centers technique without centers. The gun shot as well as I do. Since my lathe doesn’t have a dial on the tail stock I setup a test indicator off the carriage on my lathe to use the dro for measuring reaming depth. With the curve not in line with the lathe I could see about .002” movement from the wobble. As I got more confident I lined the curve on a later setup I got no movement. The last one I even was able to figure out how to time the curve of the barrel up when installed.
Below is how I figured to measure the reaming depth. The test indicator is on the nose of my reamer holder.