Will the b-square or weaver no-gunsmithing mount leave a mark on my blued gun .Does anyone have experience with these mounts taking them on or off ? Do they loosen up with a steady diet on magnum loads ?

In my opinion the B-Square mount is junk, to put it mildly. Fits on with a couple of miniature screws. A real Rube Goldberg contraption. I tried one on my 29-2 and after one look at it, took it off and threw it away. If you want to scope one of these Smiths, have it drilled for a proper job. A member at my club just sent his back to S&W and had them properly done.

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-jwk-
US Army '72-'95

I have to agree that the B square is junk. It will not hold zero well and it will mar your gun badly. Krehmkej's post is right on.

My 617 came with an Aimtech sideplate mounting rail. This one wraps around the cylinder and uses 2 sideplate screws in addition to clamping on the top strap.

There were a couple of problems that caused me to remove it and take the gun into work and drill and tap it to the new mounting scheme using a verical mill. At the same time I also did the same for my model 67-1. One was that the crane retention screw supplied by Aimtech only had about 1 1/2 threads engaged, which meant that it would have been very easy to strip the threads in the frame. Frankly, I'm surprized the previous owner hadn't stripped the threads, apparently he was either a very good mechanic or an engineer because the average yokel would have stripped those threads. The second is that it left a mark on the sideplate that I had to sand out using 220 and then 400 grit wet sandpaper. Fortunately, with a stainless gun doing something like this is simple, if it had been a blued or nickle gun it would have meant living with the mark or having it refinished.

I'm with the others here, have your frame drilled and tapped to the new standard mounting scheme using #6-48 threads. Not only will it make you gun rail ready, you'll also have the option of mounting a reflex sight such as a J Point on a direct mount instead of using a rail.

BTW, I have the J Point on my 610 and like it enough that I'll be mounting one on each of my revolvers when I can afford more. On my 610 it sits very low on the gun and it allows the POI to be within 1 inch of the dot from 20 feet all the way out to 130 feet. However, that was a happy coincidence of a flat shooting round and sighting the 610 in at 100 feet. Once I get a J point for my 617 I expect that I'll have to experiment to determine the optimum sighting distance because the 22LR is NOT at all flat shooting from a revolver.

thanks , Thats what I thought and appreciate the help .