I hope those of you with experience in chambering work can help me with this question. I have a barrel I plan to send out for reboring and rechambering to a different cartridge.

How much would you have to set back a barrel chambered for a 30-06 case in order to rechamber to 308 based case ? Would it be .300, .400 thou or more ?

I have also looked at the Mauser cases, but was worried they have too much taper to work. Would an 7x57 or 8x57 require more or less set back than an 308 case ?

Wyatt

For the .308, it is .5 inch. For the 7mm, it would be more; but you can get there by cutting off the threads and and re threading, which is best anyway. Often it is best to get a new barrel, as reboring is not cheap. It depends....

+1 dpcd


Reboring is seldom cost effective unless you are just jumping bore diameters and not chambers. 243 to 308 or 270 to 30-06 etc. All that is recut is the bore and the neck. The old chamber is left intact. As dpcd said, if you want to recut the chamber it's almost as cheap to go to a new barrel. The stress relieving and steel quality is so much better in today's barrels too.

In a lot of cases there simply isn't enough main chamber area on a barrel to lop off the thread extension and start over and you lose an inch of barrel length. Another problem that crops up from time to time with re-rifling is that the muzzle of the barrel can sometimes develop a slight internal flare, even with cut rifling. Most of the time when you order a new barrel, even with cut rifling, the maker will recommend cutting off the first inch on either end.

The sporter barrel in question came free with a batch of parts I picked up. It is large thread , 23&5/8" long (metric), .550" at the muzzle, chambered for 270 Winchester with a pitted bore. I planed to throw it out, but used it recently to experiment with barrel contouring on the Lathe. The contour came out nice enough that I would like to rebore the barrel and use it.

One company says that it can be rebored to 280 Remington. Another says that I would need to go up to 30-06 to ensure the old rifling is removed. I don't know who is right on that one! I have plenty of 30-06's already. The barrel is quite light so I would rather not bore to 338-06 or 35 Whelen. I thought that if it could be set back to a different case family I might have more options. ...Thoughts ?

Wyatt

Thoughts? Yes, use it as a tent stake and get a new barrel.
Moving to a 280 leaves a very small room for reaming so that is why some will do it and some won't. .003 is not much, when you consider that is only .0015 per side; I would not do it. But if you are intent into pouring money into it, a 30 caliber is the only option, BUT new 30 cal take off barrels are very cheap. What is the action?

I have not decided on the action, but have several options available.

Both companies I contacted said a 338-06 would work. My fear is that with such a slender barrel the recoil would be sharp. I noticed most of the barrel manufacturers only do .338 bore on heavier contours. Maybe I should quit while I'm ahead.

Wyatt

Yes, a 338 with a .550 muzzle is too light, for me anyway.

Just my thought but why spend so much time effort and $$ to try and make a silk purse from a pigs ear?

Get you a new barrel and you will be a lot happier in the long run. If you have doubts now they won't go away. They will always be in the back of your mind.

Yes, what Ram said. BUT, if you just can' t resist dumping money, your Mannlicher idea would work. BTW, 20 inch is too long for a Mannlicher to look right, to me. 18.5 is the number. Look at originals and you will see the proportions.

quote:

BTW, 20 inch is too long for a Mannlicher to look right, to me

+1 I have a 358Norma that is 20.5 and it is WAY to long to look right to me.