If that is true, it may be the lawyers at it again. You have two recognized frames in the Colt Single Action Army Revolver. The first ones, with the cylinder base pin held in by a screw in the front of the frame (there may be a little cross over in the two, so please don’t nit-pick me on this. I am very familiar with the Colt SAA, but not “expert” in the little details of them) are considered safe to fire only with black powder loads. The second ones, with the cylinder base pin held in by a spring-loaded plunder appearing to have a screw in both ends and going laterally thru the frame sides, are for smokeless powder.
It could be that an absolute full load, velocity and pressure, will really take a BP frame colt apart.
There may be other .45 Colt-caliber weapons were a full load of smokeless powder is close to the red line as well, although right of hand, I can’t think of any.
Again, I don’t know if that is the answer, but if the information that began the thread is true, it is a good bet. By the way, I would not class the current factory load as a :pop-gun:" load of any type. For those who have fired them in light guns like a Colt SAA, if the recoil is any indication of “power” they are a stout load.