The cylinders are indeed slightly (~.020") larger, and Dave Scovill said in the Feb-Mar 2010 Handloader "...it is folly to buy an inexpensive imported replica and then horse it up to match +P loads in a Colt, or expect it to shoot as well as a finely-tuned and polished Colt or U.S. Firearms Mfg. or custom six-gun, such as a Turnbull Restorations built on a Colt or U.S. Firearms Mfg. Co. parts." Mine is a Turnbull Restorations model with color-cased frame, hammer & trigger, and Carbona bluing and engraved cylinder. It is also as tight and well-fitted a SAA as I have ever examined, and I suspect it will shoot +P loads with alacrity, though I have no need or desire to try to make a magnum out of it. I called & spoke with someone at Turnbull who didn't wan't to gon record who said they are as strong as the Ruger BHs, but he wouldn't recommend using the Thompson Center loads (as if...). Since it is such a nice pistol, I will probably not exceed +P, and that on occasion. I have SBHs & no need of a shot-loose work of art...
Thanks to all for you input - much appreciated!
Cheers,
George J.