I had a standard 7.5" .454 SRH for years. While the .454 240gr Hornady XTP's (2,000 fps) could make a 1.5" 5-shot (Always allow a flier - er, flincher!) group from the scoped SRH off of scorched sandbags, the .45 Colt cowboy loads never made it past 4" groups under similar conditions. I assume the slow rifling twist really favored fast rounds. Additionally, the shorter cases will leave powder residue - and lead and copper shavings - due to the case mouth step being so deep for the longer .454 cases. Do use a proper size bronze chamber brush regularly, along with a decent cleaner - especially before going to .454's.
Incidently, I loaded some mild .454's - actually, 250gr LRNFP over mild amounts of Titegroup in .454 cases - to get ~950 fps. It was very comfortable - and grouped much better than any .45 Colts - even hit close enough to those 240gr Hornady's to reliably ring a 12" plate at 110yd handheld without adjusting the sights. I would suggest that as a far better alternative to different case length/power ammo for the SRH.
Now, for real fun with a packable 'big bore', try a 4" 625 - like the new 625JM version. It's MSRP of $50 more than a stock 625 buys some nice stocks, etc - for just a few bucks more than the SRH. You can shoot the .45 ACP's all day in this one - and some custom .45 Auto Rims, too, for hunting, etc. For .454 level loads, you'll still need that SRH - and, from my experience, lots of naproxum sodium and wrist braces for the CTS. I guess I am wimping out these days...
Stainz
