Is a centerfire SB2 a 20ga, 12ga or 10ga frame ?

[Slackdaddy]

I know the 12ga USH is a 10 ga frame, and the 20 ga USH is a 12ga frame.
And if I want to use center fire barrels start with a centerfire gun (frame),
But do the SB2 frames fit 20ga, 12ga or 10 ga barrels ?

Thanks,
Nick

[quickdtoo]

SB2 rifle frames work with all barrels except the 10ga and 12ga USH barrels which are 1.2" in diameter which is .100" bigger at the chamber swell, the 10ga SB2 shotgun frame has a larger opening in the frame to accomodate the larger chamber swell. The 10ga SB2 is likely so named due to being a heat treated alloy frame, but the smaller 1.1" rifle and shotgun barrels won't work on it.

Tim