Gunsmithing New Barrel Trimming?

[diderr]

How much on each end of a new barrel blank is recommended for trimming off? Or does it matter? My thought is on each end of the barrel blank there may be different tooling speeds, and it might be enough of a difference than the rest and cause accuracy to suffer.
thanks.

 

[Parsons]

I am obviously no gunsmith but on breach end I would just face off the barrel so all manufacturing stamps are faced off. I don't think that end is a big deal on being cut off to ensure lands and grooves run all the way to the end as you will be chambering and cutting them away any how. I have heard take an inch off of muzzle end just as a precaution. Again I am no gunsmith, just what I am doing in class.

 

[Gene Poole]

I usually like to part off about a half inch or so at the breech. That way you have the original stampings for future reference or to give to the customer.

 

[Aeon1]

Most manufacturers recommend 1" minimum for muzzle. Breach whatever you want or need to fit stock contour. I cut the ends to within ~.050" with a bandsaw and finish to length facing in the lathe.

Why would you think a potential difference in tooling speeds would make an accuracy difference?

 

[Geno C.]

The normal reason it is recommended to take an inch off the muzzle is because in the lapping process the end of the threads are sometimes oversized.

 

[BillyGoatMachine]

Why would you think a potential difference in tooling speeds would make an accuracy difference?

Possibly building up too much heat and stressing the metal?

 

[Aeon1]

Possibly building up too much heat and stressing the metal?

IMO with proper tooling that's a problem that doesn't exist although it's been brought up that using a cutoff tool to cut the muzzle might distort the bore with the heat generated. I've seen some heated discussions over that.

Edit: Maybe the OP was asking about manufacturer caused machining stresses. If so the answer above about the lapping is the reason for the recommended trim length.

 

[scotharr]

1" or so off the muzzle to eliminate bad effects from lapping. Nothing needed off the breach since the first couple inches get turned into chamber...i.e. the rifling is cut away.