SB-2 USH with Specific Rifle Barrels?

[jkpq45]

Hello Friends,

I'd like my first H&R purchase to be as "handi" and versatile as possible--wanted to know if the 12ga USH/10ga SB-2 frames would physically fit a 32" 45-70 rifle barrel or if there's a different dimension from bolt lug to breech face, etc.

Some numbers for thought:

10Ga 3-1/2" SAAMI @ ~11500 psi, 0.939" OD: 7994 lbf bolt thrust
45-70 SAAMI @ 28000 psi, 0.608" OD: 8129 lbf bolt thrust

Thanks,
jkpq45

[quickdtoo]

It will fit, but not right due to the difference in chamber swell size as mentioned before in your other thread, you'd have to bed the barrel in the frame to make it work right. Your numbers are incorrect, the rim size of the 45-70 is irrelevent, case head size is .505", shotgun case heads are hard to measure due to the internal construction, actual breech(bolt) thrust is dependent on internal case head area, using the exterior case head diameter is just for ball park comparisons which don't work well with shotgun hulls.

Tim

http://stevespages.com/page8d.htm

http://www.riflebarrels.com/articles/custom_actions/bolt_lug_strength.htm

[jkpq45]

Thanks for your patience, Tim.  I really appreciate it.

So, to be the most conservative (again, focusing on the shotgun SB-2 receivers,) I'd imagine I can assume the full SAAMI 10ga pressure acting across the smallest interior case surface area as the "design lug thrust".  This would be the maximum force exerted on the breech face that, likely, is trying to shear the recoil lug or make the break action break open.

In comparison, I can take the full SAAMI 45-70 pressure acting across the entire OUTSIDE case area (again, just to be conservative) and see how the numbers compare.

In the end, you mentioned bedding the barrel to the action--sounds like I need to make up the 0.05" gab between the rifle barrel and the shotgun SB-2 receiver, correct?  Is this only for aesthetics or will it effect the way the firearm functions?

I know the simple answer is just to buy two receivers, but again, I've got my thinkin' cap on.

Thanks again for your thoughts and consideration, I appreciate your patience.

jkpq45

[quickdtoo]

Bedding is essential if you want it accurate with a rifle barrel, unfortunately the bedding that's been done has been done on the frame which would prevent the use of a 10ga barrel, see Fred M's barrel fitting link in the Accurizing section of the FAQs.

Tim