In Feb '23 I posted about a loose hammer pin in my pre-B 75. The gun shoots well, but the hammer cams to the right when the trigger is pulled in SA. A lot, like 1/32". It turns out the left side hole on the hammer was poorly machined and is too large. It is an '87 pre-B with the wide hammer. I could replace the hammer and solve the problem, but the wide hammer is why I got the gun. I got no replies to my post and eventually took the gun to my local gunsmith. He explained the "correct" way to fix the hammer is to drill and install an oversized hammer pin. Very expensive. He also suggested shimming the hammer pin, which evidently is something done fairly often with revolvers.
I emailed Lance Shively at triggershims.com. I gave him the pin diameter and an outside diameter I was shooting for. He replied within 24 hours (on the weekend) with two possibilities. His website is pretty neat. You can select packages designed for a specific revolver, or in my case, order the exact number of shims you want. I ordered 8 .140 x .281 shims in .002, .003, .004, and .005 thicknesses. Cost was minimal, he shipped that day and they showed up color coded for thickness.
Now the fun: how to get those little buggers onto the pin and into the gun. I "glued" them onto the hammer using a tiny amount of moly grease, then gently slid the hammer in the gun. It worked a lot better than I expected. I assembled the hammer 4 times trying different shim combinations and it only took four to five minutes per try. If the shim didn't stay over the hole as it slid in, it could be pushed down from above and then centered using a dental pick through the hole in the frame. I used a 2mm punch to center the assembly, then gently pushed the hammer pin through. I ended up with .004 on the left and .006 (two shims) on the right.
Before shimming, pressing hammer left and right, without hammer spring installed:
After shimming about 60 to 75% of the movement is gone:
My frame is not very pretty on the inside (imagine that!) and has a ridge on the right side where the shims make contact. I think if the frame was flatter I could have gotten a little more shim in and a little less movement. The camming is greatly reduced and trigger pull weight is unchanged. Definitely worth $12.50 and an hour of fun in the shop. Honestly it took me a lot longer to reassemble the pre-B safety than to shim the hammer...
