Seeking some help from forum members if possible.

One of the hammers on a non-rebounder double I have is proving quite "sticky", in that when it is pulled back to full cock (either from half cock or all the way from resting) and the trigger then pulled, it occasionally only drops so far down as the half cock rather than completing a full drop to hit the striker.

I have had this expertly seen to with the as-original locks being fully removed, oiled etc but I fear the issue may be returning. We initially thought it may be wood shrinkage etc when the gun was taken outside, but it has happened in indoor temps as well.

Has anyone any experience of this as I would appreciate some thoughts/solutions?

You can tell if the locks are operating ok when removed from the gun. If so, the lock is rubbing on something when it is installed on the gun.

Loosen the lockplates slightly from the stock--not more than one turn of the lockplate screw, pull the lockplates slightly away from the wood and then test the hammer. If the lock functions properly then it has something to do with the wood, as Daryl said. I've often used this process with flintlock rifles and it works fine.

Just a simple thought, could congealed oil be causing the sluggish nature of the lock? I doubt that this is the problem but sometimes we overlook things... What type of oil was used?

Steve - no excess/congealed oil as the locks have been fully cleaned/serviced as well as the internal wood where the locks fit in.

Joe/Daryl - if it is the wood, what could have caused this and is there an easy solution?

Water/humidity will cause wood to swell like crazy. It varies with different climates.

Over the years since the gun was built the wood may have lost moisture & shrunk. This could result in the sideplates being pulled in too far when the screw is tightened putting the works in a bind. Should this be the case the above suggestion of loosening the plate screw/s should also relieve the situation. If that works then you have but to determine whether its binding from the wood fit or the plate being sprung & then fix whichever it proves to be.

I know that this comment will be greatly frowned upon but oh well here it goes anyway. If the problem is determined with the wood and not a warped plate, find a competent smith to scrape away some of the inner in-letting for the locks and bed them properly with one of the many compounds available, the smith should know what areas to relieve to allow the locks to function properly. If a good job is done no one will ever know without removing the locks and bedding compound is far more stable than wood. Of course it has worked this long with out an issue so bedding is probably overkill, however it should give years of service to the gun without a hitch.

This is an excellent solution, IMO. I have a Pedersoli muzzle loader that I shot, quite a bit, in NMLRA vents. Over a few years of frequent cleaning and frequent disassembly/reassembly, it became fairly easy to tighten the lock plate screws a bit too tight. Doing what Steve said above, worked fine for me. I used a few small brass finishing nails, to determine the depth of the bedding(Brownells) and the lock plates now have a stable place to seat, without binding anything.

Make sure they didn't put the main spring hook in the wrong way round. They'll fit but stick....just like yours

Put them back the right way and they'll work perfectly again...might be this?

T