Disassembling GPR Percussion Lock

[Mike_AK]

I thought I would go ahead and install the Lyman lock on my GPR kit and see how I like it before I order an L&R lock. Has anybody ever disassembled one of these? I cannot see any obvious way to release the spring tension so it can be taken apart. I am used to seeing a pin hole in a guide rod for this sort of thing, but no apparent way to keep the spring compressed on the Lyman lock.

 

[StewartLeach]

Alaska Mike:

The Lyman [and other similar coil spring locks] are a pain to dis- and re- assemble, but it can be done. Wear goggles or face shield. Remove the sear screw, sear, sear spring and plunger. Next install a small C-clamp to put pressure on the bridle, leaving access to the bridle screws, which you will remove. Loosen the clamp, pull away the bridle and there will be enough slack to disengage the mainspring strut.

Another way to do this is with a small pair of Vise-Grip pliers. Pull the hammer all the way back, and fasten the pliers to the strut where it is exposed in front of the boss on the lock plate. Remove other parts. This technique may damage the surface of the strut. Polish it down before reassembly.

Warning! It is easy to lose the tiny little piece called the fly, which sits in a well in the tumbler. Immediately place it in a pill bottle. If this piece hits the floor, it will transmogrify into a spent centerfire primer.

Remove the hammer, and then polish the parts with trigger stones and/or very fine emery wrapped around a popsicle stick. Polish enough to take off surface roughness and sharp corners.

I made a special tool from an old screwdriver to simplify reassembly. Cut the blade off square, then grind a 1" long taper on the end, such that the end looks like a capital letter D. Then use drill and bit or Dremel and bit to put a small indentation at the center of the straight side of the D.

Reassemble all but the mainspring and strut. Secure the lock plate in vise or to bench, start the end of the spring and strut pair into the boss on the plate. Engage the tit on the end of the strut with the tool, and push forward and down until the strut drops into engagement with the tumbler. [I've often thought of drilling a cross pin hole in the strut when the lock is apart, but it would have to be mighty small hole.]

When reassembling, lubricate with Moly Slide or similar moly loaded grease. Tighten the screws firmly, but do not over tighten. Test for free movement of sear and tumbler.

Favor Center!

White Fox

 

[necchi]

I just let the hammer down as far as it goes,
take a needle nose plier to the capped end of the spring guide and slid it back a bit and out,,simple. There isn't that much pressure on it.

I generaly do this with the lock plate in one hand and the pliers in the other.
You need to keep a keen eye when watching me do this, it takes all of 2.3 seconds. :grin: