Custom chamber reamer for a gas gun?

[thefitter]

What would be some of the important considerations and differences in specing a custom chamber reamer for a gas gun such as a M14/M1A over a bolt gun?

Thanks

 

[Grump]

As far as I'm concerned, none other than avoid minimum *diameter*.

My first one, the 'smith said he headspaced halfway between the mid-point of the SAAMI and USGI tolerances. Don't remember the numbers but that meant that any ammo sized to the Wilson age's "max" *ammo* headspace still had a lot of clearance. Cases sized midway between min and max on the Wilson gage lasted 4-5 firings and started breaking.

On a different one now but it's also kinda long. Since I backed the sizer out to bump the shoulders back .004-5, I'm up to 5 loadings on new brass and will probably another 3 out of them.

AFIAC, when the magazines are right, loosey-goosey chambers are not needed and feeding/chambering reliability is not a problem.

 

[thefitter]

As far as I'm concerned, none other than avoid minimum *diameter*.

My first one, the 'smith said he headspaced halfway between the mid-point of the SAAMI and USGI tolerances. Don't remember the numbers but that meant that any ammo sized to the Wilson age's "max" *ammo* headspace still had a lot of clearance. Cases sized midway between min and max on the Wilson gage lasted 4-5 firings and started breaking.

On a different one now but it's also kinda long. Since I backed the sizer out to bump the shoulders back .004-5, I'm up to 5 loadings on new brass and will probably another 3 out of them.

AFIAC, when the magazines are right, loosey-goosey chambers are not needed and feeding/chambering reliability is not a problem.

Thank you.