You might look into one of those mounts that attaches to the frame under the grip panels. Another option is to switch gears and buy a S&W M&P CORE.

 

Another option is to switch gears and buy a S&W M&P CORE.

Thanks but I've already got a couple of Glock race guns

 

tlen is right about the mount for the frame....


just be carefull if you mount to slide . the more weight you do the harder it will slam.

 

The Burris FF III would be great to put on a 1911. I have 2 of them on my Min-30's and love them. When I can afford another FF III I will be putting one on my RIA TCM.
Burris makes at least three 1911 bases to mount the FF in the rear dovetail. Colt Govt, Kimber standard and Bomar, and 1911 Novak. I'm thinking the Novak one would be the closest but still might require some fitting to the Rock dovetail.
http://www.opticsplanet.com/burris-mount-fastfire.html
Here is a FF III on a Kimber:

A TRS-25 would be bigger on a 1911 compared to a FF III, the FF is not much much bigger than an Adjustable Target rear sight. And I doubt battery life of the TRS-25 would be near as good. Some size and weight comparisons (both without mount included):
TRS-25---- 2.4 inches long, (much taller than the FF III, I could not find the height spec for the TRS) weight 3.7 ounces, 3,000 hours battery life
FF III---- 1.8"x 1"x .9", weight less than 9 /10th's of an ounce, 10,000 to 20,000 hour battery life (I got varying answers on the FF III battery life, but as it has a feature that turns it off after 8 hours to save battery life, it should last much longer).
I could not find a pic of a TRS-25 on a 1911, but here is one on a Ruger .22, should give you an idea of the size difference.

 

Figure out what rear sight cut you have and order the correct Burris mount. If you run out of elevation you might need a shim but I didn't on my STI or Les Baer. I've got 1000's of rounds on my BFlll's with zero issues. Nice thing about this set up is there's no permanent mods to the gun.

 

I've put a Bushnell First-Strike on my Rock TCM by modifying an EGR Novak mount for a Docter sight. I don't really see that other than convenience would recommend a Pickatinny rail on a slide. If you intend to use that larger form of sight, a direct mount to the frame or one of those under-grip systems might be best explored.