The aforementioned load of 7.5 grains of Unique is a mild, easy-shooting load that will not strain your gun. I have probably burned up more Unique than any other powder in 45 Colt because it is excellent for the caliber. 7.5 grains works well and is not a red-line maximum load, so you can shoot a lot of it without worries. Yes, I run more than 7.5 grains in mine, but it's a different gun, so there's that.... All else being equal, (250-255 grain cast lead bullets), I have experimented with this powder from 6.0 grains to, well, more grains and found excellent accuracy at all levels. But for the gun in question here, I would not go above 8.5 grains at the maximum. Since the Cimarron is of similar strength as a Colt, you should not try to make a magnum out of it. To get the most velocity without hurting the gun, there is one powder that is outstanding: Genuine fffG Black Powder; with a maximum charge, it can deliver 1,000fps, but it loads differently than smokeless.... There are a few smokeless powders that can get you close to that, but none better. Heck, just stick with 7.5 grains Unique and be happy.
Now if we were talkin' Ruger Blackhawk....but we ain't.