There's a few small, thin flat springs inside that are many times the source of the problem in the '77. One is a 3-legged thing and it breaks easily. It powers the hand and cylinder bolt.
The sear spring is a single leaf spring but with 3 bends in it,2 rather sharp and one gentle bow inbtw the 2,, it also gives problems when it doesn't have enough power and you try to bend it a bit.
Trigger spring is a simple single leaf but very short and stiff, It breaks easily if over bent.
The cylinder bolt is an L shaped part with it's pivot pin machined or cast right into it. It will often break the long extension arm right off that draws the bolt back and out of engagement.
Dixie GunWorks of all places used to sell a cast replacement for these back in the 70's and 80's as well as a few other repro parts. They were about useless even after filed up and fitted. But it was about all that ws around. Some welding/brazing to rebuild the 'new'part usually resulted in success.
The D/A sear is another dinky part that gives it up easily. The repro part of those the same issue as the cyl bolt.
Some repaired '77's would leave the DA system dead and just rely on the SA to have a usable pistol.
Even in the 70's and 80's you couldn't find any good parts!.
Jack First Gun PArts does list quite a few parts for the 1877 now including those annoying little springs & mainspring.
They also list the DA sear, hand (another trouble maker), trigger and the cylinder stop.
I've never bought any of the parts from them so I can't vouch for their quality. Some are repro I'm sure, but how good I don't know.
CNC machining of odd parts would seem to be the way to go now as opposed to the rather crude cast method of making them.
He has screws and other small parts available too.
Colt 1877 Double Action Lightning revolver – Jack First Inc.
Looking over his list I see that a couple of the more common to break parts are 'out of stock',,not unusual I guess.
The last one I worked on was one that was converted to 22LR. That was a neat little pistol, but it didn't make any inprovements in the mechanics.
It's just one of those designs where it appears they didn't have a clear plan. They just kept altering parts till things would work.
The 38cal Lightings will accept 38Sp WC as the chambers are bored thru,,no shoulder for the 38Long Colt that it is actually designed for.
That's what Colt did on it's 38Colt revolvers than,,bored the cylinder straight through.
You will find that feature on early Colt SAA in cal 38 Colt also,,the cylinder bored straight through w/no shoulder. I forget when Colt started to use the shouldered chamber, but it was well after the 1877 was discontinued.
Easy on the loads, easy on the gun play. No guarantees on the mechanics of the pistol.
