Handi SB1 or SB2 action?

[Mississippi Mud]

I just bought a Handi 45.70.  It has a new ultra stock and a new factory install buffalo classic barrel.  The action is a Northwest Trappers Association commemorative.  I remember reading some posts about interchanging barrels and limitation depending on whether you have an SB1 or SB2 action.  How can I tell what action I have on my Handi?  I don't plan on changing it out anytime soon, but just trying to deterimine whether I could in the future.

[quickdtoo]

The best way is to call H&R and give em the serial number, they'll tell you what barrels can be fitted to it. Look in the FAQ, there's a link to pics of the different frames, but that's not the best way to tell whatcha got.

If the second letter of the frame serial number prefix is N or newer and it's an SB2 frame, any barrel can be fitted except the 10ga and rimfire barrels. Older barrels can't be fitted with any of the * marked barrels on the accessory barrel list.

Tim