GPR Lock Disassembly

I'm closing in on finishing my first GPR kit build. It's a 50 cal percussion. I'm finishing the barrel, rod holder, tang, trigger guard, heel plate, wedge escutcheons, forend cap, butt plate, and rod guide with vinigar. The rest of the metal will be the original black colors. Except for the lock. I do not want for there to be just one piece of case hardened metal on the rifle. So, I need to disassemble the lock, sand the finish off, and "pickle" the face of the lock plate only. I figure I will disassemble the lock assembly, lay a piece of cotten in a flat bottomed bowl, lay the lock plate on it face down, and put just enough vinegar in it to keep the cotton soaked but not enough to immerse the plate.

My question is: Is there a specific sequence of disassembly/assemby of the lock assembly and are there any traps I need to be aware of? I've never taken one apart and I don't want to remove one screw and have pieces fly all over the place.

I figure this sounds like a dumb question to you experienced guys but I relate it to taking down a Ruger Mark II 22 pistol. It seems ridiculously simple till you go to put it all back together unless you've planned everything out ahead of time.

You have two springs on the back side of that lock. They need to be removed to remove the rest of the parts. The mainspring should be a coil spring, if its a Lyman, that has a "strut" up its center. The strut should have a hole in it, that is exposed when you cock the hammer back to full-cock. Put a paper clip, or similar small diameter wire in that hole, and then lower the hammer. The mainspring should come out easily then.

Use appropriately sized GUNSMITHING screw drivers to remove the screws that hold the parts in the lock plate. Set them aside in the order in which they were removed, so that you can put them back in the opposite order.

The other spring is the sear bar return spring, and it should be a leaf, " V" spring. Unscrew the screw holding the spring to the place, keeping your thumb on the spring itself. A small amount of compression will be needed to release the spring, but I use a taped-jawed, set of needle nose pliers to remove this spring, with the Slightest of squeezes.

The mainspring will release the Tumbler. You can then remove the bridle screws with help to hold the tumbler against the lock plate. The bridle also keeps the " Fly", if your gun has one, in place on the tumbler. Secure this fly as soon as the bridle is lifted. The Sear is usually held with just one screw, so its easily removed. To separate the hammer from the tumbler, bridge the lock plate across the jaws of your bench vise, to allow the tumbler to move. Remove the large headed screw on the outside of the hammer, at its pivot. Then, use a piece of brass, small enough to fit inside the square hole in the hammer, but not so small as to fit down against the threads in the tumbler that held that large headed hammer screw. Tap on the tumbler, to push the tumbler away from the hammer. The hammer will be stopped by the outside of the lock plate, and the top of your bench vise jaws. Have a helper put their hand below the vise, to catch the tumbler when it separates from the hammer. You don't want it damaged. When I don't have a third hand to help, I have stuffed rags under the jaws of my bench vise, to "catch" the tumbler for me.

You might want to put a witness mark on the hammer, and the tumbler, so You know what side of the square stud the hammer should be oriented on to work properly when you put the lock back together. Since the tumbler is the Last part to be removed, separated from the hammer, from the lock plate, and the first to go back together, It should not be a huge problem figuring out what side of the square should be oriented to the hammer's axis to get the lock to work. But, witness marks help.

This might prove helpful for you to review prior to removing the lock:
http://home.insightbb.com/~bspen/percterm.html.

I haven't found a picture of the inside of the Lyman lock to show you. I did find a good picture of the L&R Replacement lock, but it uses a "V" spring for the mainspring, not a coil spring. I believe the Lyman lock on its percussion guns uses a coil spring- like the T/C does. However, if I am incorrect--- and your lock has a V-spring, then you need to obtain a spring vise to remove the mainspring from the lock. Dixie, Track of the Wolf, and other suppliers sell Spring vises. It is a handy tool to have, particularly when starting out. :thumbsup:

paulvallandigham said:

The other spring is the sear bar return spring, and it should be a leaf, " V" spring. Unscrew the screw holding the spring to the place, keeping your thumb on the spring itself. A small amount of compression will be needed to release the spring, but I use a taped-jawed, set of needle nose pliers to remove this spring, with the Slightest of squeezes.

Click to expand...

The Lyman lock uses a small coil spring inside a metalic plunger to act on the sear. I don't remember what it takes to remove. It isn't difficult though.

Salt

I just sanded the finish of the face with 320 grit paper,it's not very thick and sands off easy.Then wet a wash cloth with vinegar and lay the lock face down on it.I done mine with the hammer still on the lock and didn't disassemble anything.It doesn't take long to give it an antique looking finish. :thumbsup:

That could be a good option. What would be best of all (for me anyway) would be if I could just remove the hammer and nothing else. Then lay the plate down on a wet cloth. I can plug/coat threads and screws with petroleum jelly to protect them. I wouldn't think the hammer itself is actually holding anything in place but I don't know....

Obviously, you have never taken a Lock apart.

For your information, the hammer is part of what holds the tumbler to the lock plate. The other is the bridle. With the mainspring in place, a lot of tension is being put on the parts, and if the tumbler were to happen to back out even part way from the lock plate, that mainspring is likely to take off, and break in the process.

The only way to do what you are suggesting would be to make sure that the tumbler is held firm when the hammer is fully DOWN, and that drifting the tumbler from the hammer won't let the tumbler slip and twist partially out of the hole in the lock plate where the tumbler is mounted. Even then you still risk the mainspring from twisting off the horn of the tumbler, and jumping out of the lock, with possible breakage.


If you really want to redo the lock plate, I still recommend taking the lock apart, properly, for your own safety, and to preserve the parts intact. When you have the lock plate alone, one of the things you can now check is that the lock plate is Flat, and without curves, both front and back. You will be able to better see the tiny scratches caused by burrs on the parts of the lock, so you can remove them. You can flatten, and polish both sides of the lock plate. And you can then finish the front side of the plate any way you desire, and get a better product.

If you put vinegar, or any acid on the lock plate with the hammer in place, you risk corroding and rusting the threads of the screw and the threads in the tumbler that hold the hammer to the tumbler. Even flushing the plate with the hammer in place will cause rusting, simply because the hammer screw needs to be removed to oil the threads both male and female, as well as oil the hole in the lock plate where the tumbler fits through.

Yes, it's obvious I haven't taken one apart. The clues are my complete ignorance of the issue + my statement "My question is: Is there a specific sequence of disassembly/assemby of the lock assembly and are there any traps I need to be aware of? I've never taken one apart and I don't want to remove one screw and have pieces fly all over the place." in my original post. :thumbsup:

I had already printed off your earlier instructions in case I decide to tackle it. I was just hoping against hope that there may have been more than one way to skin that cat.

In all probability, if it comes down to it, I'll most likely just buy a new L&R lock assembly that's unfinished. That will match my vinegar finish. Since I don't have any help to hold things in place, it's worth $120 to just inlet a new assembly (and a better one) and be done with it.

I really do appreciate all your information. It was exactly what I was looking to learn.

We all start someplace. I was not dissing you. Simply making an observation.

If you buy a kit lock, you will need to buy the mainspring vise to put it together. Many of these kits require some polishing, and deburring of parts for them to fit together correctly. They are not just a simple Assemble-it-with-a-screwdriver kind of thing.

Lyman makes and sells a Screwdriver, with multiple blades, designed for gunsmiths, for a reasonable price. The blades are held to the shaft by magnets. It would be a good buy for a new guy starting out working on his guns.

I only rarely use my spring vise, because I have taken enough locks apart, and put them back together, that I now use different tools to do the same job, and not mar the surfaces of the spring. But, before I worked on my first lock, I bought the spring vise- from Dixie at their booth at Friendship. Its particularly handy to use when working with small locks( like those for pistols and very small caliber rifles.) I now own a Flinter's Tool from the Hawken Shop(Track and some other suppliers also now sell them) that has a square NOTCH in one side that will hold a mainspring for removal. I have also used C-clamps, Vise grips( padding the jaws), and box wrenches to hold v-springs for removal.

I believe that once you take that lock off your gunstock, and then compare it to the pictures I referenced for you in Bob Spenser's website, you will have a much better idea of what is possible, and what isn't. These locks are NOT complex machines. If a country lawyer can figure out how to tune them, ANYONE can. :rotf: :surrender: :thumbsup:

I covered the hammer with the wash cloth also,just tuck it around it.After all you want the hammer to look the same as the lock.You can apply vinegar to the back side of the hammer with a q-tip it just takes a few applications to keep it wet.