Hammer Replacement Issue -- S&W Mdl 66-2

[Old No7]

I'd just posted about the Mdl 66-2 on the right (see image below) in another forum here. I just picked this one up recently for a really NICE price and it appears to have been shot very little and very well cared for. I've already replaced the stock stainless hammer with a case-colored one, as I prefer those colors, but I'm having a weird issue with replacing the trigger.

This is probably the 5th S&W K/J frame that I've swapped the hammers & triggers on (MIM or stainless parts exchanged for case-colored or cased target versions), and all the other swaps were mostly "drop-ins" with minor fitting needed -- if at all.

But this one has me stumped...

With the old or the replacement hammer, and when using the replacement trigger -- the gun binds up; much more so in SA than in DA, but it's not on any one cylinder. And with the cylinder removed, it functions just fine in SA or DA. Then with the cylinder installed and the hand removed, the replacement hammer & trigger work fine together, just as the original hammer & trigger do too.

So then I moved the old/original hand back to the original trigger and tried that and now, even with the replacement hammer being installed -- all is fine.

The issue is when the original hand is put onto the replacement trigger, with the hand spring in its correct orientation -- the hand binds and it won't cycle. The bolt isn't dropping down enough so the cylinder can't rotate, but I can't tell which is the issue -- the bolt or the hand -- but with the bolt stopping the cylinder from rotating, any further travel of the hand is stopped.

When the two triggers are viewed side-by-side, they look to be identical by eye -- but I'll admit that I didn't use calipers (yet) to take and compare critical dimensions. For now, I'm reluctant to trim a few thousandths off the top of the hand as I'm not sure that's the issue -- but maybe that would be necessary if I find out there is a slight dimensional difference between the two assemblies (trigger + hand). I think my next step should be to measure from the center of the trigger pin to the top of the hand on both assemblies, and compare.

Any other ideas please?!? Thanks!!!

Old No7

 

[Alk8944]

Did you exchange the double-action sear from the old hammer to the new one? If not, do it. If that doesn't work take it to someone who knows S&W revolvers that can check it out hands-on.

 

[bobsguns]

It's out of whack. Load it with more whack & it'll run fine.

 

[ken158]

You are mixing fitted parts in two guns. Sometimes you get lucky and all is good but most of the time you need to swap the original sear and hand to the new trigger. Sometimes a new H and or T will also need a little fitting in addition to either fitting new parts or swapping over original parts.

 

[steelslaver]

It is usually the DA sear that causes problems. Sometimes changing it works, but you may need to get it adjusted. With the main aprig loose and using some finger pressure on the hammer you can observe it's operation

 

[Hapworth]

To the helpful posts above I'll add this: many folk swap and if the trigger pulls, hammer drops and gun goes bang they declare that it worked and all is good.

Without the knowledge and tools to ensure that parts are actually to proper spec in their engagement, subtle problems can be caused that will only become apparent over time.

If you're going to do it, make sure you know how to do it right or take it to someone who does.

 

[jem102]

If it doesn't already have one put a slight bevel on the top inboard edge of the hand that contacts the lugs and radius the top inboard tip of the hand slightly. This really won't hurt anything IMO and have had it work well several times. And, if I understand your sequence of part replacement, be sure the new trigger does not make the old hand drag in the window. If it is a few passes on a hard flat stone will cure it. The worst that can come of all this is needing a new hand. I have never filed the hand window and do not have the expertise to do so, yet...

 

[Old No7]

Thanks to all for the replies. Haven't gotten back to it just yet...

I think I'll avoid "more whack", but appreciate the humor.

Old No7

 

[USBP SW]

Another issue that you can check is the engagement of the trigger and cylinder stop. My friend had a similar problem with a model 29-2, the cylinder stop needed to be replaced and fitted. The dimensions of the new trigger were just different enough that the cylinder stop dropped back into the cylinder before the cylinder could start to turn. This issue was on his revolver, yours may be different but may give you another place to look. Good luck and let us know when you identify your problem.

 

[bobsguns]

Thanks to all for the replies. Haven't gotten back to it just yet...

I think I'll avoid "more whack", but appreciate the humor.

Old No7

Someone with a hammer once wrote, "There's very few things in the world that can't get solved by a few thumps of a hammer."