I have never had a problem with 44-40 cases backing out of revolver cylinders and locking them up, not even with 20.000+ psi loads, as given in Lyman 47th for strong rifles. I will admit two thing about this: 1) this revolver is a Ruger Vaquero with minimum-dimensioned chambers suited to 0,429 bullets and 2) both chambers and loaded ammo were wiped dry. Also of note, even at this "elevated" chamber pressures, I never had those "thin, weak-walled cases" stretch, either in Ruger or Rossi M92. Other than sometimes initially with new cases, I never trim 44-40 brass. Furthermore, I do not worry much about getting absolutely all of resizing lube off standard pressure 44-40 loads, either BP or nitro powders and have never had a single instance of a fired case backing out of chamber and locking cylinder. Actually, in decades of using 44-40s I have yet to see a single case of locked up cylinder from cases backing out.

I do agree with previous posters that truly high pressure, sharply-tapered cases can back out. However, even with such old-style, thin-walled cases as 30-30, often used in single-shot handguns at chamber pressures of well over 30.000 psi, I don't recall discussion or mention of these cases backing out of chambers.

I do vaguely recall stories of early 44-40 ammo, perhaps having weak primer metal and/or weak cases, resulting in lockup of cylinders. Was this really ammo or was it gun? Please do recall that lots of old or cheaply made (Italian mostly) revolvers can have firing-pin holes so badly burred by firing pins as to lock up cylinders or so sloppy as to allow soft primers to flow back between firing pin and frame, also locking cylinders.

FYI, any SAAMI-pressure 44-40 load that gets 1300 fps for 200 grain bullet from a rifle barrel -- and there are plenty with proper powder, eg. 2400, Blue Dot, etc. -- will get about 900-1000 fps from 5,5 to 7,5 inch revolver barrel. For shooting most sub-species of homo sapiens, that is well documented to be generally adequate.

Niklas