Ok, the top member of the frame (top strap) is "out of line" just as much if not more so ( depending on the model) as the arbor. One is above, one is below ( the bore line). Their frame shapes are the same but one is spread out, the other is more compact making it more robust. The arbor is supported by a robust barrel lug utilizing the shear strength of the locating pins. The force at firing is linear with minimal downward force for the pins to deal with. The rotational force imparted to the barrel assy is mitigated by the contact (butt joint) at the frame. The force at the wedge is dispersed through the arbor because of contact under TENSION ( if it IS under tension rather that just holding a "position" under some bit of friction). This particular part of the design is exactly WHY +p loads can be sustained by the design. And of course TENSION can only be applied if the wedge is imparting it and it can't do that if there's no "foundation" to allow it to exist (arbor end contacting the bottom of the arbor hole).
The second point is mitigated because of tension imparted by the setup of the design. ( done correctly, it can't "rattle" and cause destruction).
If there's no way on earth the open-top can "come close" to stress loads of " whatever ", then I screwed up because I'm already in the Ruger Only territory and showing no signs of pressure problems.
I definitely wouldn't be where I am with an original ( way too soft) but we have what we have to work with . . . which is why the testing.
The only way to make a Top strap stronger is a bigger/ thicker /wider top strap to contain the force ( not to mention boutique materials / heat treating). Compare a SAA frame to Ruger, Freedom Arms, BFR.
So I'll enjoy my testing with what I have and keep reporting. I don't mind helping but I can't help folks if they say I can't do what I'm already doing . . .
Mike
BTW, my comparison is belt pistols, the horse pistols (Walkers / Dragoons ) are a whole nuther beast!