Yes, indeed!
A good 250-260 gr Keith bullet at 800-900 fps will do a fine job in your S&W Mountain revolver. Another good bullet is RCBS 45-270-SAA (casts about 285 grs in my alloy). If you want to read about good loads with this bullet read this:
http://www.riflemagazine.com/magazine/PDF/HL 246partial.pdf
Page 12 - this is a sample (partial) copy of Handloader #246 with the full article on the RCBS 45-270-SAA bullet.
Dale53
In my opinion this is THE article for the 45 Colt, bar none!
Personally, I limit my M25 -7 to the 20,000psi loads. John Linebaugh has some loads that are in the 32,000psi area and he uses them in his M625/M25 frequently. Remember, he is a gunsmith though!
While they certainly won't blow up a firearm in good condition, they have to increase wear and tear and I decided that I would relegate those kinds of loads to my Ruger 45 Convertible rather than my nice M25!
If it will handle the 32,000psi loads, and they will, then a M625 Mountain Gun should last absolutely forever shooting 14,000psi or even 20,000psi loads.
I know that with a bullet of 280gr at any velocity, the sights are NOT going to be able to come to POA/POI, no possible way. In fact, mine will not shoot that way unless I use a 230gr bullet or below, period.
I can also tell you this: If you shoot a 280gr bullet even in the 20,000psi data, you are not going to want to shoot a lot of them at one time!

Get you a lever gun to shoot them in. They are a real hoot! Besides, that is a great combination, a Smith M625 and any lever gun in the same caliber!
