The newer 10ga and 12ga Ultra NEFs are the SB2 strong action just like their
big bore rifles. The only difference is shotgun has a larger diameter
firing pin. The SB2 is an investment cast, properly heat treated,
action like a Ruger 77 bolt gun. And it is almost twice as strong as the
SB1 action they make, for their 12ga Pardner series, their 20 ga Ultra,
and various others.I have both 10 and 12ga on SB2 and so far they've
taken a beating and are still tight.And the 12 has a thumbhole stock
and weighted to 15 lbs and it even handles 600 gr at 2500, from
long brass case, that fits in the lengthened chamber.Ed