There are a few things that anyone who owns a Sidelock with a V-spring can do to lessen the chances that the spring will break an arm.
First, round all the edges of the spring. Most of these springs are Cast- not forged, and they will arrive with lots of burrs on the edges that need to be removed. While working on removing the burrs, using fine files, you can round the SQUARE corners of both arms with the file on both arms, altho if you choose one over the other, the arm of the spring that moves is the one that needs the most help. ie., on frizzen springs, its the TOP arm that moves when the frizzen is opened; on a mainspring its the Bottom Arm that moves when the tumbler is rotated to cock the hammer.
You will note that even a knife edge file will not get down into the Notch at the bottom of the V-spring. There, use a long strip of emery cloth, Fine, to extra fine, to get down as far as possible into the slot to help you round that inside square edge. Clamp the spring in the jaws of your benchvise, first on one jaw, clamping the sides of the arm, not the flats, using soft jaws to hold the spring and not gouge or dent the spring with the teeth of the vise. When you have rounded the exposed arm's edges( it doesn't take much- you are not producing metal sculpture here!), turn the spring over, and do the other arm.
Square edges induce stress to metal, making a place where the metal will fatigue, and eventually can break. Today's springs don't have the same fine finishing touches that you find on museum quality original arms from the 18th century.
Once you have rounded those edges, and the burrs have been removed, install the spring in the lockplate again, and look across the length of the lockplate to see if any part of the spring is Rubbing against the lockplate other than where the spring is supposed to be attached. If there is any part of the moving arm that rubs against any part of the lockplate, then do this:
Second: Draw file the side of the spring arm where the metal is touching the lock plate to remove enough metal to stop that from happening. Rubbing also induces stress to the steel spring arm( Whether the spring is a "V-spring", or a coil spring on a strut. I will get to coil springs later.) Take a couple of strokes of metal off the side of the spring arm, reinstall it on the lockplate, and visually inspect it again. If you still see contact, mark the spot on the spring arm with a ink pen, or pencil, and take the spring back to the vise. File it off.
Filing the side of the arm may remove that slightly rounded corner edge you put on the
Springarm before, so round the finished product again. It won't take much effort since you know what it should look like, and you simply are matching the same rounding look that you have on the rest of the spring arm.
MAKE SURE THAT THE LOCKPLATE IS FLAT! More than one lock has been presented to me, that had a bowed lockplate.
I used a metal machinist pocket ruler laid against the lockplate on my first foreign made lock, and removed most of the binding up of parts by simply straightening the lock plate. I rarely see this with American made locks these days, but I did see it once. The bowing was nowhere near as severe as what I had on my first gun, but it was there, nevertheless.
I straighten lock plates by putting them in the soft jaws of my bench vise and then slowly tightening the jaws of the vise against the lockplate- with all its parts removed, of course.
Third: Not all, but some of the traditional side locks have the upper arm of the mainspring fitting up into a slot between the lock plate and the bolster. The end of the upper arm, which is stationary, is often turned at almost a 45-90 degree angle to the line of the arm, and then forged, or cast flattened, to fit into that slot.
Understand that the closer you push the two arms together- particularly when only one arm actually moves!--- the more stress you put on that moving arm. Stress eventually will cause work hardening and take advantage of any stress fracture line to break.
The Upper arm often can be filed thinner at that "Tab", so that the tab goes up into the slot further. Metal can be filed off the end of the tab to let the spring arm go up further in the slot. This "opens" the V-spring, so that cocking the hammer back to full cock does not put as much tension( stress) on the moving arm. This lightens the hammer pull, by reducing the tension of the mainspring. We are talking about changing the Angle of the v-spring, compressed by only 1-5 degrees, at most, but it can do much to change the tension of the spring, and its working life.
I try to do this whenever I find a mainspring that compresses the two arms together and then requires further compressing of the longer end of the moving( Lower) arm in order for the hammer to reach full cock.
If the v-spring is designed so that the upper arm is attached with a screw, then I have no other choice than to consider reshaping the "hook" on the working end of the moving arm, or replacing the mainspring altogether.
Fitting a new tumbler, with the notches moved to reduce the tension on the mainspring is another option, which is also a PITA to do, and well beyond what an average shooter with basic tool skills can be expected to do. The same comment applies to working on a spring with a stirrup and rod that attaches the end of the moving arm to the tumbler.
Coil Springs for mainsprings: Most of the factories making these kind of locks use springs that have too MANY coils, to insure reliable ignition. It a CYA idea that some bean-counters came up with to protect the companies from lawsuits.
If you remove the lock so that you can see the mainspring actually work, as you slowly cock the hammer back first to half cock,and then to its full cock notch, you will see the coil spring compress, and then begin to move side to side like a rattle snake, with the coils rubbing against the steel strut that runs up the middle of the spring.
Rubbing is not good. These springs may last longer than the average shooter will ever shoot the gun. However, we always have those shooters who shoot their guns a lot- dozens of shots fire each week, and hundreds fired each year. That kind of use will accelerate the wear on those coils, if nothing is done about it.
Take the coil spring off the strut. Believe it or not, I have seen burrs and sharp edges on those struts that act like files against the tough coil springs. Remove the burrs, and round the corners of that strut.
Now, using a dremel cutting wheel, cut coils off the spring, to shorten it, and Stop the "Stacking". "Stacking" in a coil spring is what causes the spring to snake back and forth as the hammer is cocked.
How many coils? Count the number of curves of the spring away from its straight column when the hammer is at rest, and remove at least one coil for every two such curves to start. In most cases, you will need to remove one full coil for every curve. But, go there slowly. The spring is easily and cheaply replaced, but the first time you do this kind of work, you nerves will need some consideration.
Just removing the stacking on coil springs will improve lock performance, and reduce wear to the lock plate, the tumbler, and even the sear so much that after firing thousands of shots, the internal parts will still look like new, and work that same way.
The amount of force you must apply to cock the hammer back will be noticeably less- to the point that you begin to fear the gun won't fire. I have fired off my share of percussion caps, in my shop, without powder in the barrel to insure that the lock still works! :shocked2: :bow: :surrender: You can use a trigger pull gauge or a bathroom scale to measure the amount of force needed to cock that hammer back to full-cock. If the force is 10 lbs. or more it will work just fine. Most factory locks have that tension well above 20 lbs. :shocked2: :shake: :nono: And, the prime cause is the springs with too many coils, so that stacking is required to get that hammer cocked to full-cock!
Oh, you can buy the small bits sold for dremel tools, and use them in any powered hand drill, if you don't already own a dremel tool. The only time I tried to cut these coils with a wire cutter, I took a big divot out of the edge of my cutters, and the coil spring laughed back at me.
:idunno: :blah: [ THERE! I just saved you the cost of replacing your favorite wire cutters. :grin: ] :hatsoff:
