WSAR15: There are some very common faults on a lot of replicas. Probably the most common is the bolt popping up too early. This is controlled by the tail on the spring not positioned correctly on the stud/cam of the hammer. This popping up of the bolt too early doesn't do any mechanical harm but the bolt rubs against the cylinder and in time creates a noticeable shiny line. Another common trouble can be a bur on the racket teeth and as I said, most replicas have some sort of mark on the cylinder so you can test to see if any trouble only occurs on a particular chamber. Yet another issue is a cylinder that doesn't quite line up to the barrel and spits lead around the face of the forcing cone- you test that with a range rod. I don't think much can be done to fix that, maybe recut the forcing cone.
Some folks want a hair trigger and put a drill rod in the notch area to accomplish this. Filing the drill rod insert down until the hammer just barely cocks.
My recommendation is to DO NOTHING. In many cases "fixing" the gun only makes it worst. Replicas are modestly priced and the whole thing is to experience the guns used yesteryear. We are often making replicas better than the originals.
A lot of these replicas are case hardened in wear areas. Filing and re-working removes this and you have to re-do the case hardening. On trigger noses, etc. You ought to be making jigs, etc. to insure proper filing angles, etc. Incorrect filing on racket teeth is an irreversible error.
On the Colts, there was supposed to be tiny pins between the chambers and when you lowered the hammer, it was supposed to rest on the pin head- that's why there is a groove in the face of the hammer. Some replicas don't have the pins but that's a pretty easy thing to do.
I'd get some quality screwdrivers and grind then down to EXACTLY fit the slots in the bolts. That way you can routinely take the gun apart for cleaning without chewing up the bolt slots.
