LOCK POLISHING & TIMING

The last few months, I have been discussing one way to approach building or modifying a "custom" civil war period long arm. Together, we have investigate why we are building a musket rather then buy one, and over the last couple of months we thought about exactly what weapon we would build. A logical first step in perusing the now defined goal of building a non-stock musket is to acquire and assemble the parts for the lock of the desired arm. This method presents the would-be armorer with a taste of the feast to come. It is better to pay up to $200 for a complete set of lock parts and find out you don't really enjoy musket making, then it is to have parted with more then $1,000 for a complete set of musket parts and make the same discovery. Assembling and polishing a gun lock is a good way to get your feet wet in the building business, and your subassembly may even be immediately useable to you.

A polished lock benefits anyone who uses a civil war musket or carbine - even breech loaders can benefit from a timed and polished lock mechanism. In a standard Springfield or Enfield lock there are six major bearing surfaces which will benefit from polishing. These surfaces are: the mainspring and plate surface; the tumbler and plate surface; the tumbler and bridle surface; the bridle and sear surface; the sear and plate surface; and the hammer and external plate/stock surfaces.

The exterior components - hammer, plate and stock - are sometimes overlooked during the timing process. A smooth lock on the inside can not compensate for a hammer that binds on the stock during ignition. Another problem can be a rough hammer rubbing the lockplate face during hammer fall. If you miss this when you assemble the lock, you will eventually see bright marks on the lockplate where the two surfaces are binding during ignition. Good fit between the hammer screw, hammer and tumbler are also important. The hammer screw must fit tight and stay tight. If the hammer becomes sloppy, or loose, the power of the mainspring will be dissipated during ignition and may lead to hangfires or ignition failures.

On the inside of a lock, plenty of friction means slow firing time, inconsistent performance and perhaps the early demise of one or more parts. Regardless of whether you're building a new lock or just polishing up your old one, start with all the pieces separated and cleaned. Inspect each and every surface for burrs. On used locks, inspect for signs of wear. Bright streaks on the parts, or obvious gouges, are obvious signs of a lock in need of polish.

To polish your lock, you'll need some 300 and 600 grit wetable sandpaper or polishing cloth, available at hardware stores. Stop by an auto parts store and pick up some medium or fine valve grinding compound as well. I only use a metal file for two or three strokes, if at all. You're probably better off without a file for starters.

So, you've got your parts and polishing supplies, how do you start? The first thing I like to do, and this is when I might use a file, is to smooth up the inside of the lock plate. I check for burrs around the contact point for the mainspring, and make sure that the mainspring fits cleanly in the designated pin slot. Use you coarser grit, and make sure you're working the plate with smooth, FLAT motions. The worse thing you can do is create more problems then you solve by dishing the surface with a bunch of depressions made by circular, rounded motions. I've used metal rulers, shims, even files to wrap my paper around, but the choice must be flat. If you choose, and your polishing a large lock, you can lay your paper on a flat surface like a table edge and keep the paper still while moving the lockplate. Whatever you do, do it with a FLAT support.

After polishing the face of the lockplate, the tumbler is next. The tumbler transfers the power of the mainspring to the hammer. Any friction or binding on the tumbler directly affects lock timing. The surface of the tumbler that rests on the lockplate should be polished completely flat and smooth. Unfortunately, most tumblers you buy are pretty rough, and so are some of the ones that come in off-the-shelf muskets, too. Because the tumbler has so many surfaces and angles, it takes slow, painful patience and elbow grease to work this surface smooth. The payoff, though, is in quick lock time.

The opposite side of the tumbler from the lockplate side is the side that binds against the bridle. Here again, painstaking work is required because of the odd shape of the tumbler. Smooth of the inside of the bridle too, and once you've got that tumbler moving friction free you're halfway home to quick lock time and better shooting.

For some reason, the sear is sometimes overlooked during polishing and assembly. The sear is perhaps the most important piece of a lock to a competitive shooter. It transfers the pressure of the trigger into action, and binding here can cause enough extra effort that your shot becomes errant. The surface between the sear and the lockplate should be so smooth a rumor wouldn't stick to either one, and the sear/bridle margin also requires attention. When the trigger is pulled, the shooter wants absolutely all effort to transferred directly to the sear nose, slipping the tumbler free for the weapon to function. Most sear today are manufactured by a process which produces edges around one or both sides of the sear. The sear, then, really rests on these edges, not the entire surface of the sear. The wise lock polisher polishes the edges so they are smooth, but still raised enough that the amount of bearing surface, ergo friction, is reduced considerably. Modern sears are so rough, that one of the best cures for a less then three pound trigger pull is a replacement sear that is not polished. I recently helped a shooter who had a light trigger pull with this swap, and he went to almost six pounds just by changing the sear. A little polishing, and we got it right where we wanted it.

After polishing all the bearing surfaces, I like to assemble the lock with a dab of valve grinding compound on the working surfaces. I work the lock carefully about 20 times, rinse the compound off, and try the action. If it still needs a smoother get, I repeat the procedure until I achieve the results I'm after. Be careful with the compound around the tumbler notches, I like to keep those crisp. DOn't be afraid to assemble and disassemble the lock. Put in the time now, and that lock will last for many happy years.

A polished lock makes shooting and skirmishing more productive. While your out there waving that thing in the breeze, you want the quickest lock time you can safely get with a three pound trigger pull. So, don't over polish that lock. You still have to stay within the safety guidelines, so check you pull occasionally while polishing that lock. And, until the next time, shoot safe and have fun.

(C) 1994 Tom Kelley
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