turnin a 1 inch green moutain barrel muzzle round

[DuncanvonYeast]

I have a 1" gm barrel that I want to use for a target rifle barrel and I want to make a brass short starter that fits over the muzzle. I don't know if the barrel will banana because those barrels have a lot of internal stress.( I tried to swamp long story short it banannad and was destroyed) 

[Hungry Horse]

I'm a little unclear just what you are doing. Are you turning the entire barrel round, or just the muzzle so it will accept a socket type bullet starter?

  Hungry Horse

[B.Habermehl]

If you are only turning the muzzle end back a 1/2 inch or so for a socket type guided starter. The barrel certainly will not move, be sure the work is done between centers on the lathe. It may be that the crown of the barrel will need a touch up after the turning is complete. BJH

[Daryl]

The muzzle should not 'bell' (expand) when turning it round for your guide bullet/ball starter.

Are you only turning off JUST the corners of the flats?

This usually is only a problem with high strength, modern ctg. barrels where turning the muzzle for a sleeve sight base can cause the muzzle to expand - sometimes.

In ML barrels, I think this is unlikely to happen.

What does GM say?

[JCKelly]

I don't know exactly how modern cartridge barrels are made, except that some have the rifling cold forged into them. Those must have very high residual stresses, probably compressive in the bore.

My GUESS is that your GM barrel will expand, the bore will get maybe 0.001" or so larger in diameter, from turning it. That is not so great for accuracy.

I'd be really interested in knowing what GM says. They are the guys who know, what they say may be another matter.

[hudson]

I have turned several 15/16 and 1 inch barrels for a starter and/or for appearance without a problem. I am fortunate in having a lathe which will accept a barrel through the spindle. Snug plug is turned to fit both ends and used to dial in the barrel. Four jaw chuck and a second (spider) chuck is used on the opposite end. This same setup is used to crown and cone a barrel. With black powder barrels I wouldn’t expect problem. High power button and hammer forged rifled barrels can be a problem as I understand it, multiple steps in stress reliving required. Have run into some B.P. bullet barrels that were button rifled as long as a major brand maybe not a problem.

[Scota4570]

How are you all indexing the false muzzle???  Using a linotype cast of the bore to line it up then finishing drilling the dowel pins?   

[Daryl]

I got the impression this was simply a guide bullet starter that slipped over the muzzle without rifling in it and tapered smooth inside - not a piece of the barrel itself. Maybe I misunderstood.

"I have a 1" gm barrel that I want to use for a target rifle barrel and I want to make a brass short starter that fits over the muzzle."

[Bob Roller]

I got the impression this was simply a guide bullet starter that slipped over the muzzle without rifling in it and tapered smooth inside - not a piece of the barrel itself. Maybe I misunderstood.

"I have a 1" gm barrel that I want to use for a target rifle barrel and I want to make a brass short starter that fits over the muzzle."

There's NO reason the guide starter won't work. I have made a number of them over the last 60 years.
Turn the muzzle to get rid of all the octagon for about one inch the bore the starter to .001 over that
dimension.With the bored starter still in the lathe bore it to a dimension about .015 under land diameter.
On my .451 I bored and reamed the starter to .438 and made the plunger from .4375 drill rod.
I made mine with a locater pin on the barrel and a tall pin to block the front sight. The starter can be notched
to witness the locater pin.
Have fun.Been there,done that.

Bob Roller