Reassembling S&W 66 Problem...

[brockgl]

Heya folks!

I bought a very nice used S&W Model 66 w/4" barrel yesterday, and I couldn't be more excited, because it was exactly what I've been looking for!

I of course examined it very well before buying it, and also when i got home. Its action was as smooth and stable as my new 686, and its cylinder lockup was even tighter.

However, this was the first used gun I have ever purchased. I usually purchase new, because I take very good care of my guns, and I like knowing how they have been treated in their lifetimes.

However, the 66 is out of production, so used is my only real option.

Nevertheless, I wanted to detail strip it and clean and oil all the lockwork and inspect the internal parts, etc... I wanted to do this before I relied on it as a carry piece.

I have detail stripped and reassembled all 3 of my S&W revolvers before, and I feel very comfortable doing so. I know the correct way to remove the side plate, and I know which parts are tricky with springs, etc... So, I wasn't worried about this one.

But something in the reassembly has me stumped!!

I get the gun completely reassembled except for the hammer block and side plate, and while in this condition the action works flawlessly. The hammer cocks smoothly, the trigger releases it perfectly, and the cylinder cycles with no problems.

However, the minute I drop in the hammer block and install the side plate the action takes on a problem.

There is a "hitch" near the very rear of the hammer cocking. This happens just before the hammer would reach its cocked position. Sometimes the hitch is so strong that the hammer will not even cock. Other times (after disassembling and reassembling again) the hitch is not enough to keep it from cocking, but enough to make it a very rough last pull at that point.

Again, once I take the sideplate and hammer block off the action functions perfectly as normal every time. It's like the hammer block is getting caught on something and dragging in its canal along the sideplate. But for the life of me I can't figure it out!

Has anyone had this problem? And if so can you lend me some advice on where to look?

I will add that this problem did not exist when I bought the gun and has only come about once I've disassembled and reassembled it. I have been very gentle with all the parts. It is very unlikely that something has been damaged or bent.

Man, I just hope someone has experienced this before... Thank you!

Brock

[Edit: I will add this-- if I install the side plate WITHOUT the hammer block the gun cycles and cocks perfectly. This leads me to believe that the trigger/hammer posts are straight. I happened to have an identical hammer block laying around and I tried it to see if there was a slight bend in mine. But both hammer blocks cause the 'hitch' so no cigar.]

[brockgl]

I took some time to take some pictures of the interior of my gun, as well as the assembly process I am using.

Hopefully these can be useful to folks for other purposes as well, who knows...

First Stage

Second Stage

Third Stage

Fourth Stage

Fifth Stage

[James K]

Try screwing the sideplate on, then increasing the tension on the mainspring by tightening the screw at the bottom of the front strap. It looks like the tension is not enough to bow the spring properly and the hammer is contacting the end of the spring head on, which will give the result you describe. If that is the case, it has nothing to do with the hammer block.

Jim

[brockgl]

Jim,


Thank you so much! The problem is completely fixed, and the mainspring was the culprit.

I am not sure if the screw wasn't screwed tight enough, but I began loosening the screw and testing moving the main spring to different angles, and when I screwed the screw back in with the spring at a slightly different angle, the problem disappeared!

I never would have guessed it to be such a simple issue. I have been working on this hardcore for over 24 hours now.

Thank you for the recommendation!