I just got a .44mag. barrel, when I slugged it, it was .431, I called H&R, I was told their standard .44mag. is .431 with +- .002 tolerance.
I have no idea why they selected .431 as standard, but had I known that, I would never have ordered one.
The .308 Win. barrel I received was also a disappointment, .310 groove diameter, again ,I called and was told standard was .308, but +- .002, so .310 was in specs.
Not happy about this, at all.