My factory K frame (64) hammer has the firing pin in the hammer and it is under spring tension. The spring forces the pin down but it can move upward against the spring tension.

I have a K frame factory bobbed hammer with the firing pin and it moves freely but is under no tension. When installed, this hammer sometimes binds or contacts the firing pin channel and appears to catch.

What gives? Is this a common occurrence? From searching, I was under the impression both versions worked. The hammers are identical other than one being bobbed and the spring tension.

I really want this bobbed hammer to work. Does anyone have a moon rock factory bobbed spring tensioned firing pin hammer ?

All you need is a hammer nose cut for the spring, and a hammer nose spring. The hammer nose rivet can be re-used. Installation instructions should be found in the FAQ's.

Is this what I need?


Power Custom Smith Wesson Hammer Nose Rivet-Style K Frame Case

The hammer nose pictured on the link is cut for the spring, so yes, that should work. You don't really need a new rivet, but, if it is included, why not. However, if you got to Numrich Arms and search for S&W parts, Model 66, item number 47, S&W part #322850A, is the hammer nose spring - $2.45, and Item #48, S&W part #1087940, is the hammer nose you need - $6.00. Hope this helps.

**UPDATE
Turns out the hammer I had was fine. However, the firing pin was oversized .005 and was sticking in the firing pin hole. This was enough to bind the action.
Had the pin thinned and now it works as it should.