Is this a helicoil?

[hawkeye2]

"But then again, I've had a barrel come in that's .5% off on groove diameter and their response was a brush off, that it's within specs."


1/2 of 1% is just under 3/10,000 of an inch on a .50" diameter hole, is it possible to work to tighter tolerances than that? Is it possible you meant 5%? That would be .025" in a .50 bore.

 

[Zonie]

The way I figure it, 0.5% of .500 is .003 or, three thousandths of an inch.

In my opinion for the rifling in a muzzleloading barrel that is designed to shoot patched balls a +/- .003 tolerance for the rifling groove diameter is reasonable. If the barrel was designed to shoot modern jacketed bullets, it would not be reasonable but since we can't talk about those things on the forum I won't say what the tolerance I think is reasonable for those is.

 

[hawkeye2]

Yep, got 1 too many 0s in there. +/- .003" is probably closer than a lot of imported barrels.

 

[longcruise]

An update. I sent the barrel off to GM a couple weeks ago and received it back today repaired with a new helicoil and a new nipple. They paid shipping both ways. The barrel is as good as it ever was and I'm perfectly satisfied with the way they handled it.