The only one I've used is the 7/8"x5"-16oz, it fits in the stock bolt hole of a Handi almost perfect, I used a leather pad on the front of it against the stock bolt head as a cushion, and a piece of PVC pipe behind it to take up the space. A couple wraps of electrician tape so it fit snug, but could still be pulled out with the ¼" bolt.
I just bought a Tikka T3 Lite 338WM, might be installing one in it, I'll use a piece of PVC pipe supported in expanding foam to mount it in...if I need it!! Another T3 owner had that done to his by a gunsmith.

Tim