Barrel profiling

[strobes]

Need help here as I'm doing this first time.
I have a SS barrel that is 1.25" straight and need to cut it to 1.055" for savage action then part of it to .90" and down to .75" at muzzle.
About 10" or so from .90" to .75". It is on manual lathe by adjusting tail stock.
I see two option 1. between centers 2. keeping chamber end in 4 jaw chuck.
With option 1 I'm afraid chatter and it may walk from chuck in option 2.
Any suggestions? Thanks.

 

[bapayton]

I've done it both ways.

If you've got your tailstock offset the canted barrel will likely not stay in place in the 4 jaw. Think I ended up using a piece of heavy gauge copper wire around the barrel shank as sort of a fulcrum point. Worked better but not great. The center in your tailstock will also wallow out the muzzle unless you have a ball center which most hobbiests don't. You will need to fairly constantly check tailstock pressure. If you forget the chatter will quickly remind you.

Between centers didn't have enough rigidity for me and you'll still have problems with the tailstock chewing up the muzzle.

I've had plans for a pneumatic follower but have never put it together.

I'd suggest straight turning as far as you can then blend with tapered cuts. In the end it'll probably be faster and less frustrating even with multiple setups.

That's been my experience, many people here have much more experience than myself.

 

[Dusty Stevens]

Its going to chatter like a sob no matter what you do unless you have a lathe big enough to run a tank barrel thru the headstock, but most people try it at least once. My suggestion is send it to @Stan Taylor and get him to profile it on the cnc machine set up to do this exact operation

 

[Walt Krafft]

Dusty is correct. When people ask me to do this for them I quote $400 which is more than a new barrel of the correct profile will cost. But that is how much time it will probably take to get it done with an acceptable finish. If you have a follower rest you will have half a chance. Otherwise get some good files and lots of emery paper because you are going to need it.

 

[bapayton]

I turned a full taper once, like Dusty said, that's about all it takes to learn your lesson.

I'll blend short tapers for myself but that's where time/benefit ratio stops.

 

[DaveTooley]

I've done it several times. I hate doing it and refuse to do it these days. I did it between centers with a lathe dog driving the barrel. Steady rest and turn no more than 6" sections at a time. Even then you need the right insert that doesn't set up a lot of cutting stresses. Long angle lathe file to blend it all together and you're good.

 

[tobnpr]

Stoopid question...
Why not make your life easier, and do it as a shouldered barrel instead of a nutted "prefit"? A lot less material to remove...

 

[Rich S]

I did one between centers. I used a steady and did small sections at a time. Wasn't too bad but was time consuming. It was when I first bought my lathe and was a good learning experience.

I talked to one guy that runs them through the headstock. He advances the barrel out and supports it with the tailstock as he goes. That way he is always working close to the chuck. He's using CNC so is able to set the taper he wants. If I was going to do another I'd likely try form of this

 

[Rebar]

I just contoured two green mountain barrel blanks between centers and driving them with a lathe dog. I don’t think I would do it again but it was a good learning experience for me. The first one was a 22” SS blank for a 350 legend and it chattered the worse out of the two. I turned it down to a Remington mag contour. The second one was a 25” 4140 blank for a 450 bushmaster that I turned down to a Remington varmint contour. I didn’t have much chatter on this one but I had more experience by then. I was running at 150 rpm with a feed rate of .004 ipr and a .020 doc. You need a very sharp tool bit hss. I also made a center with a shoulder for the lathe Chuck.

 

[bapayton]

The "learning experience" is why my next hunting barrel will be turned similar to a Mauser military contour. Plus I kinda like the utility of the look.

In regards to contouring, I ground a cheap brazed carbide tool to a sharp point and used basically just the tip once chatter got terrible. Any contouring tool with any radius is trouble in a hobby sized lathe unless using a follower.

 

[carlsbad]

sell the barrel and buy the one you need.

 

[Cigarcop]

Send it to John @ Keystone Accuracy he re contours barrels daily on a CNC.

 

[GenePoole]

I've only done 2 profilings. The first was with the offset tailstock and it was a chatter nightmare. The second, I tried a different tack: figured out the profile I wanted, calculated the literal taper per inch, then cut each inch. Finished with a spinner and belt sander, then a final polish. Still tough, but more predictable. Definitely not worth the time.

 

[Shawnba67]

I mounted a yard stick to the shield on back of lathe, put an indicator on carriage. I could turn in 0.001 every 1/4" or so for taper. You have to have a steady and can really only get a few inchs from it before chatter gets bad.
I found changing my feeds slightly occasionally helped a little. Think from 300tpi to 320tpi and back. (Just an example of slight chsnge)I have on occasion cut from tail to head then head to tail. Im a cheap bastard , Im not sure I will ever do another!

 

[10XSHOOTER]

Is it a cut or buttoned barrel? If it's a cut rifled barrel you might get away with it. but a Buttoned barrel you're lible to change the bore diamentions.

 

[DaveTooley]

I've only done 2 profilings. The first was with the offset tailstock and it was a chatter nightmare. The second, I tried a different tack: figured out the profile I wanted, calculated the literal taper per inch, then cut each inch. Finished with a spinner and belt sander, then a final polish. Still tough, but more predictable. Definitely not worth the time.

Gene
When I saw the insert you were using I cringed. I have that one and it is a chattering SOB. This is the insert I use for turning when rigidity is an issue on my manual machine. Which is most of the time.
https://www.mscdirect.com/product/details/46861613

 

[DaveTooley]

Is it a cut or buttoned barrel? If it's a cut rifled barrel you might get away with it. but a Buttoned barrel you're lible to change the bore diamentions.

If it's a match grade barrel that has been stress relieved after rifling, additional turning won't be any different than the maker turning it smaller when it was originally made.

 

[338 Mollett]

I have found it to be faster using a 4" hand grinder,with about the same finish.

 

[carlsbad]

If it's a match grade barrel that has been stress relieved after rifling, additional turning won't be any different than the maker turning it smaller when it was originally made.

Agreed. Even if it hasn't been stress relieved, it would take hella residual stress to change the ID. I hope my barrels, and your barrels, don't have huge residual stresses.

 

[jdh47]

Whose barrel? Most makers will contour it for a fee. It would be the best option unless you just want the frustration.