http://en.wikipedia.org/wiki/Mare's_Leg
This tells us that the original Mares legs were Win 92 sawed off rifles.
The Henry does not look exactly like a Win 92 nor a Win 94.
I have a Win 94 in 45 Colt and I have only shot handloads in it at ~ 20k psi ~ 22 kpsi in Quickload calculations. It kicks like a mule. A 6 pound rifle sending a 250 gr bullet at 1536 fps, means I need a recoil pad.
The SAAMI registered max average pressure for 45LC is 14 kpsi.
When Nosler lists Ruger loads for the 45LC, 11.3 gr Unique, 1.6" 250 gr JHP, Quickload thinks that Nosler is at 27 kpsi
When Speer lists Ruger load for the 45LC, 10.5 gr Unique, 1.59" , 260 gr JHP
Quickload thinks that Speer is 32 kpsi.
Speer says it is 25 kpsi.
My Ruger Blackhawk has chamber walls:
0.071" ~ .074" to the outside
0.059" ~ .061" between chambers
My guess is that the Marres Leg is going to have a chamber wall much thicker than the Ruger Black hawk. Chamber thickness will probably be the weak spot in revolvers, but the lever action weak spot is probably the long narrow falling block and how the frame holds it.
The Rossi stainless Win 92 is rated for 454 Cassull [ 10,300 pounds thrust].
The Henry Marles leg is also offered in 44 mag.
If the Henry falling block can take the 44 mag thrust [~ 5,200 pounds thrust], then it can probably take the 45 LC at 32 kpsi [~ 5,200 pounds thrust]
So my guess is that the Henry Marles leg is probably going to take the Ruger loads, but the recoil would be obnoxious.
I bought an old 45LC revolver today, and the seller told me specifically that 200 gr XTP 9 gr Unique is the accurate load. That looks like 12 kpsi in Quickload.
I could guess he was going to say Unique. That seems to be a key accuracy powder for wimp loads in the 45LC.
The Unique loads in 45 Colt make small groups.
Heavy bullets make groups higher on the target, as recoil lifts the muzzle.
Lighter bullets make groups lower on the target.
I would just keep trying the wimp loads, if I had a Mare's leg.
