LOCK, STOCK & BARREL, Part One

Pulled the trigger and the gun said "go"

The shot fell over in Mexico, Honey, let me be your Salty Dog

Traditional American Folk Song

One approach to shooting improvement is to acquire a better understanding of the mechanics applied inside your weapon, and how they interact with the success of your shot. When you pull the trigger, and the gun does indeed say "go", why does the shot fall over in Mexico?

A musket or carbine has three main subsystems which together form the whole, and they are: the lock, the stock and the barrel. The barrel provides the chamber for holding a load, and ignition, as well as providing the best platform for sights. The stock provides a framework for mounting the barrel and necessary hardware to ignite and propel the load, as well as the means by which the entire weapon is assembled. The lock ignites the charge. Of the three components the lock is the most complicated, but it also ranks highest in importance. A barrel is either good or it isn't. A barrel has only two parts - breech and barrel. Understanding the barrel and how it works is a simple matter.

A lock can make or break a shooter. A strong, quick, dependable and reliable lock is often the missing component along the road to improved competitive shooting. And, a rough, untimed, undependable lock can be a safety hazard at reenactments and skirmishes.

How a Muzzleloading Lock Functions

When force is exerted on the trigger, the trigger swivels on its' mounting pin and engages the SEAR of the lock. A SEAR SPRING, mounted directly above the sear, applies just enough pressure to keep the sear and trigger in contact without interfering with ignition. The NOSE OF THE SEAR, at the opposite end of the ARM OF THE SEAR, which engages the trigger, is in contact with the TUMBLER. The TUMBLER is that part of the lock which rotates the HAMMER onto the nipple. The TUMBLER has two notches located on its' circumference, the half-cock notch and the full cock notch. If the sear is in the half-cock notch, and the trigger is pulled, the gun should not fire. If the SEAR is in the FULL COCK NOTCH, the tumbler will be released, sending the hammer towards the nipple. The power and speed with which the hammer moves is provided by the MAINSPRING. The MAINSPRING is usually attached to the LOCKPLATE by a pin at the vortex of the V-shaped spring, and it is attached to the tumbler by means of a FLY. The FLY provides a more consistent release than direct connection between the TUMBLER and MAINSPRING because of the small radius of the TUMBLER. Most FLYs resemble a letter "S", with little bumps on each end to engage the MAINSPRING and TUMBLER.

A BRIDLE holds the TUMBLER centered and square to the LOCKPLATE, and provides the required spacing for the other parts to function smoothly. The LOCKPLATE provides the mounting area for not only the parts, but for mounting the entire component into the stock with one or two LOCKPLATE SCREWS.

How a Revolvers' Lockworks Function

While a revolver pistol, and most breechloaders, have completely different physical designs, the applications are similar. In a pistol, the half-cock and full cock notches are cut in the base of the HAMMER. The top of the trigger engages these notches, eliminating the need for a sear and tumbler. The MAINSPRING bears directly on the trigger, providing percussion ignition power.

Diagnosing Lock Problems

As you can see, there is a lot going on in the split-second it takes for any lock to function. And, a lot can go wrong in a little time.

The most frequent cause of heavy trigger pull is friction between the lock parts and/or the lockplate. It is also one of the easiest problems to correct. If your musket requires white- knuckle force to fire, you can disassemble the lock, and with a flat file and some 300 grit wet-dry emery paper, polish the surface of the lockplate smooth. Then, polish the inside (the side that wears on the lockplate) of the Tumbler and Sear. Do not alter the shape of any parts, merely polish off the usual casting/foundry marks which account for 90% of heavy trigger pulls.

If polishing the lockparts reduces your trigger pull, but you're still unhappy with the force required to fire the weapon, you should seek out an experienced shooter or blackpowder gunsmith. The nose of the sear and the full-cock notch will need to be polished and reshaped to effect less strenuous efforts on your part, however, under no circumstances should a competitive shooter reduce his trigger pull below 4 pounds, and a reenactor is probably better off with a 5 pound trigger pull.

Broken lockparts are the bane of competitive shooting, as they usually occur in the middle of competitions. Spare lock parts are the best insurance against lock "downtime". If you are going to carry spare parts, make sure that you have final-fit them to your weapon before you need them. Replacing a broken or chipped tumbler with a rough, ill fitting one is not a progressive substitution. Consideration for carrying extra lock parts should also include an extra hammer screw, especially if you have noticed yours working loose on any occasion.

The best place to find parts, including lockparts, for Civil War weapons is at one of the National N-SSA Skirmishes at Fort Shenandoah. Many sutlers there will have original parts for original guns, as well as replica parts. I always start my part searches at S&S Firearms (718-497-1100), Bill Osborne (414-473- 5444) or The Regimental Quartermaster (215-672-9020).

When a competitor can not cock or fire his weapon or is having other ignition problems, an understanding of the lock mechanics involved will speed the recovery process. A lock that won't stay cocked usually is suffering from a cracked or loose bridle (parts out of alignment), a chipped tumbler (notch won't engage sear), or a piece of musket cap has worked into the lock and is interfering with the tumbler and sear connection. A lock that won't fire once cocked may have a broken mainspring (no power to tumbler) a broken sear arm or a broken trigger. A cracked bridle may also result in this malady. A lock that fires from the half-cock notch usually has a chipped nose on the sear or a chipped half-cock notch.

Your lock should be removed, inspected and cleaned annually, or more frequently if you shoot a lot. Look for cracks in the bridle, tumbler, and hammer. Then verify part alignment carefully, taking care to insure continued serviceability. Remove all signs of rust, and lubricate the working parts and all surfaces of the lock. For pistols, breakdown the pistol and inspect the surfaces where the trigger and hammer interact for cracks, etc. Finish pistol inspections with a good cleaning and lubrication.

Shooters have a fascination with gun parts, and the more you know about how your weapon works, the better you'll be able to work your weapon.

In closing this month, I would be remiss if I failed to mention the improved safety at Ft. Shenandoah since the Spring National. I have been to at least 5 skirmishes since then, and I have never seen better safety habits. The Potomac Region of the N-SSA has even begun conducting mandatory Safety Classes. My hat is off to every member who has helped to contribute to this change.

Until the next time, shoot safe and have fun.

(c) 1992 by Tom Kelley
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