doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Lefever Sidelock

I have two Lefever sidelocks the barrel to receiver lockup is slightly loose. The adjustment mechanism on both of them uses a spanner bit. I ground out a flat head screwdriver that fits into the heads just fine, however neither adjustment screw will budge. placing a small bit of paper into the hemispherical
indentation on the receiver locks op both guns perfectly. What am I doing wrong. Help!

Those screws have not been budged for near a hundred years. Try to soak them in a good penetrating oil. I also find that it helps to back them off before you try to advance them. They are just stuck screws that need the normal means to loosen them. Oil, heat, cold, tapping or vibrating to loosen them. Whatever works works.

That damned Lefever, you'd think he would've thought ahead and used an allen wrench fitting, something with leverage, knowing his guns would still be put to work over a 100 years later. He just wasn't thinking ahead .

The later guns used a slotted joint screw. The earlier ones had the spanner head you mention.

I have never had some come out easy. They all take some mew me to get them free.

Other than the two types of head, IE the spanner & slotted I also believe there were two types (At Least) of threads used. Some have been noted to have a taper thread while others have straight threads. I have only had two of these loose & both had straight threads. It is noted though that while the had straight threads the tap was not run completely through the knuckle joint of the frame, so the screw gets Tight as it comes to position.
The recommendation to back the screw up before trying to tighten it is "Extremely Good" advice.
It should also be noted this screw is to adjust for hinge wear only, "NOT" for bolt wear. Once the barrel is On Face, if the bolting is still loose then it needs work on the bolt & should not be adjusted further via the ball screw.

I can add a little to the good advice that has already been given. Many of the popular penetrating oils that folks swear by won't penetrate more that one or two threads deep on those century old Lefever compensating ball screws. I have a small quantity of Cabot's Tasgon which was banned by the EPA in 1981 due to its' creosote content, and I reserve it for those extremely stubborn gun screws that just laugh at Kroil and many other imitators. I have also had good luck lately with pure Oil of Wintergreen. One of these screws on a D.M. Lefever crossbolt gave me fits, and I almost gave up hope of ever moving it without doing damage to the gun or screw. I put it aside for over 6 months with Tasgon on the threads and it came out like it was never stuck. Patience is the most important tool for removing one of these when it is stuck. If you gall the threads, no penetrating oil on earth is going to help you.

Another method that has helped me is to look for one of those old electric soldering irons with the heavy copper tip. I find them at flea markets and swap meets for a buck or two. You don't need the huge ones with real high wattage. 75-150 watts is plenty. You grind the copper tip to make a perfectly fitting screwdriver point for the screw you are trying to remove. Soak the screw with good penetrating oil and apply the soldering iron to the screw slot and brace it upright with it plugged in for about 15 minutes. Let it cool some and re-apply more penetrating oil. Repeat this for as many days as it takes. This localizes the heat on the screw instead of heating the whole action knuckle with a torch. The repeated heating and cooling seems to help the penetrating oil get into the threads. I've heard that Lefever may have used some early threadlocker compound which would prevent penetrating oil from getting in. The heat may break this down if true, just as heat will soften permanent Loctite.

Those that I have removed and measured have a very very slight taper to the threads, so if they were near the end of their travel when installed or previously adjusted, no amount of force is going to get them to go much deeper. Oregon gunsmith Keith Kearcher has recommended cleaning the threads very well after removal, and polishing the male threads on a loose muslin wheel to get a bit more travel. But if the polishing wheel grabs the screw and throws it across your shop, you could be screwed, no pun intended. Those I have measured have a non-standard thread, but I'd have to check my notes to tell you exactly what it was.

Miller is absolutely right about bolting wear. I've seen more "loose" Lefevers that need work on the bolt than the compensating screw. Fortunately, a new bolt a few thousandths thicker is easier to make than a new compensating screw.

I�ve had good luck in the past chucking a screwdriver blade into a drill press and then with the piece held firmly in a drill press vice I was able to use the drill press to firmly press the chucked screw driver blade into the screw slot and then I turned the chucked blade by rotating the chuck with my hand (in other words the drill press is never turned on). You can put an enormous amount of torque on the screw without buggering the screw slot. However, with that said, the only time I�ve had a problem was once I split the head of a screw into two pieces (I guess I really buggered that screw). I learned to be careful with the torque after that.

Keith & All;
Back when Russ was still with us he also reported having checked one of these screws & found it tapered slightly as well as a few others whom I do not recall their names. Thus there is ample evidence to this effect I have absolutely no doubt they exist.
As I said I have only checked two of them & both had straight threads, checked on OD by micrometer & pitch Diameter via Mike & thread wires. The earlier of these two guns is in the 38K SN range & the other the 46K range, both large hook guns having the slotted heads.
What I did find on both of these was that the hole through the knuckle was tapped with something similar to what we today call a Starter tap, having a long lead to the full diameter. The tap was stopped at a point where when the screw came into position it was jammed into that lead thus becoming quite tight. The actual effect is very similar to a tapered thread, IE it runs free until it just coming to position then tightens, preventing it from working loose in use, with just enough available movement left to take up any expected wear in the hinge.
It is thus not as has been proclaimed by some a "Cheap & Shoddy" means of fitting a hinge but required very precise fitting.

Note to the original poster, the Lefever is not a "True" side lock as the locks are in the frame, not on the plates. Early models were sort of a Hybrid with the sears & their springs on the plate, but all of them had the hammers & mainsprings mounted to the frame.

I vote for the soldering iron heat/cool cycles with penetrating oil-even put the receiver in the freezer between heat applications. Thermal expansion/contraction is a sure way to move the joint, to let the penetrant sink in without whacking it.

Miller, I'm very familiar with starter taps, but I have never checked the female threads in a Lefever action knuckle when I had a compensating screw removed. What you say makes perfect sense though because if the threads ran straight through, there would be nothing to keep these screws from constantly backing out as the guns were fired, sans some type of thread locking agent.

As I said, I have only measured two of these screws and both had a very slight taper thread. But I know I have a couple more in bags of Lefever parts I bought, so I will have to locate them and check them too. Interestingly, the ones I measured were virtually identical even though one was from a later D. M. Lefever crossbolt gun.