Alf, you cannot use your JM in SSR unless you use Auto Rim brass and speed loaders or another revo that uses speed loaders. Also, IDPA has lowered their pf for SSR so that any factory ammo will be OK. Any load that you use in SSR will be very mild. A major pf load in your JM will be a handfull but that is as it should be. Even though the JM grips feel good most if not all are changing to something else.
I'd forgotten about the "rimmed brass" of SSR. That's okay, I can do. Plus the web site say SSR PF is now lowered to 105! That mean you can load a 200gr to 575fps (if that's possible) and still make 115.
I could use the same gun in both ESR and SSR only by going from speed loader to moon clips! Or I could use my 66 in SSR with real soft .38special loads.
1911 Junkie: IDPA has added this little rule.
The use of trimmed (shortened) ammunition is
not allowed. Ammunition used must match the caliber
listed on the gun. The only exceptions would be: .38
special in .357 magnum, 9mm in .38 super, 40S&W in
10mm, 44 special in .44 magnum.
Don't know if USPSA has or is considering such a rule. Probably not, except maybe in production? But then IPSC & USPSA don't consider Production to be real competition, just a side match.