Repairing Damaged Screw Heads on Used Firearms

When contemplating a used firearm purchase the first thing I look for is rust. The next thing is "boogeredup" or damaged screw heads. Nothing screams amateur and abuse like a messed-up screw. By using ill-fitting screwdrivers countless side-plate and stock screws have been damaged beyond repair. Or have they? Nego tiating a price is on the buyer’s side when confronted by a gun that has obviously been damaged by poor gunsmithing practices.

Damaged screws cannot be hidden any easier than the hostility of a disgruntled mother-inlaw who thinks her daughter should have married an old beau who made more money than her honey. While as our wife’s mom can usually be shown the error of her judgment with time and effort, our ace in the hole is that most straight-slot screws that have been ruined can be repaired and it doesn’t take a shop full of lathes and milling machines to do this job.

Although this kind of shop setup is ideal, most of us are limited by our pocketbooks or inclination to a simpler and less expensive solution. In fact, handwork and the old-fashioned art of gunsmithing are necessary to do this job right. Common sense and Brownells again comes to our rescue. The tools we need are available. The knowledge is in this article. Unfortunately, the tools to do this job are not inexpensive, but the knowledge comes free with your subscription to this magazine. Study illustration one.

This shows a typical guard screw on a bolt-action rifle that we might see come into the shop everyday. What is actually damaged on the screwhead? As you can see, using a triangular screwdriver designed for a wood screw has literally rearranged the parallel slot. Its edges are un straightened and the metal moved by this damage is piled up on either or both sides of the top of the screwhead. We have to put this metal back What looks like a throw away screw can be saved with proper gunsmithing technique.

Notice how the metal has been piled on top of the screw head. This is what we must move back to its original position. where it belongs and, with patience, it’s easy to do. We could grind off the ridge created by moving the metal onto the top of the head, but that would be a mistake. The loss of the metal that is ground away would leave a dished-out, beveled, unprofessional-looking channel.

It would create an actual detriment to tightening and loosening this screw by having less purchase on the slot, even when using proper tools. To repair the screw and reclaim most of the metal we must use a machinist’s hammer. The metal of the slot has been moved "violently" to the top of the screw by the torque of an ill-fitting screwdriver. Tapping "gently" in the direction of the slot will move the metal back towards its normal shape. This is not as difficult as it sounds.

The secret is to use a hammer with a smooth, polished face. A regular hammer will just chew the head up.

The author feels a four-ounce hammer is most useful. I recommend first practicing on something other than an irreplace able screw or one from a customer’s gun before you attempt the real thing. Messed-up screws should be easy to find in your spare-parts containers. I save all kinds of screws, springs, and any other kind of metal that comes across my bench. You just never know when it might come in handy.

Holding the screw is accomplished by drilling a hole in a 2×4 piece of wood that is slightly smaller than the thread diameter. The screw is easily threaded into the soft wood and held tightly when inserted until the head is resting on the flat of the wood. This is the ideal way to hold the screw. In general practice I normally chuck the screw into a vice with leather or cork jaws. This will do for 90+ percent of this work. Mount this holder in your vise and go to work.

Start with light taps angled toward the middle of the slot. You will begin to understand the process when you see the metal moving in the right direction. A good magnifying visor is essential here. If your ministrations oblong the soft wood hole and the screw begins to slip, drill another hole and continue. A small, flat washer underneath the head will help stop the screw from digging into the soft wood and keep it from tipping.

The nature of this job is not to bang the piece back together by brute force but to easily rejoin it to near its original shape. But, the screw must not jiggle and move about or precision will be lost. I am a firm believer in the art of our profession. Any fool can drill a hole or pound apiece of metal into submission, but I think you will agree Save your "junk". that we have something that other people do not and that is a "feel" and an "eye" for the job we are working on.

We should have visualized the diameter and the straightness of the screw slot before we started working so we know when to stop when is almost where we want it. I guess you could do this job with a sledge hammer if you were good enough, but I rely on a variety of machinist’s hammers, some commercially available, some not. For instance, one of my most useful hammers for final finishing was once gracing a chain on a "break here" fire alarm. How it came into my possession, I don’t know for sure.

I’ve had it so long I really can’t remember but I do

use it. That’s one of the advantages of being a pack rat. I may have had that thing since I’ve been a boy. With a polished head it’s every bit a professional tool as my more expensive hammers. I find that for this job a four-ounce machinist’s hammer seems to be my best friend. I usually expect this job to take about ten minutes or less to get it ready to sand and blue after the screw is placed in its holder.

How much to charge for each screw is up to you, but personally I get a lot of satisfaction by fixing these old guns up. By carefully tapping the metal back into place we’re left with a screw slot that may be smaller than the original. Here’s where we have to lose a little bit of the metal. Think of this metal as being in the way of the original slot. The way to remove it is to use Slot Files available from our friends at Brownells.

These small files have a working edge to cut down on the slot but a smooth face that will not work the sides of the slot. Since I bought mine they must have started making these files out of gold or some other precious metal. I won’t talk about the price but you cannot do this job without these specialized files, so bite the bullet and buy them. These tools are not necessarily fragile but they will break if ham handled.

Screw Slot Files come in a set of three sizes 7, 9, and 11 which are 0.027, 0.035 and 0.043-inches (0.69 mm, 0.89 mm, 1.1mm) in width. The files are especially ground to have flat, smooth sides and only cutting edges, perfect for this job. Most of our common gun screws can be repaired with these three files. For specialized work, including the thin European style screws, Brownells also offers a much larger set with matching edgers.

The price makes my head spin, but if you take on a lot of this kind of work they are invaluable and the usual quality of Brownells products makes it easier to justify the expense. Start with a file that is slightly smaller than the original slot. What we are trying to do, remember, is not only cut a usable slot but one that is closest to the original as our tools will take us. Work it down to the full depth of the slot and then finish with one closer to the original size.

It may not be exactly the same but you will be able to find a screwdriver to fit. We are left with a repaired and usable slot but the head needs a little more work before we can say we’re finished. Take a small piece of 220-320 grit aluminum-oxide paper and staple it to an appropriate sized block of wood. Mount the block into a solid vise. Chuck the screw into a hand drill without damaging the threads. On slow speed push the head into the sandpaper and lightly polish any burrs left by our files.

Reposition the Go easy as mistakes here can misshape the head and ruin the job. head on the sandpaper as need be but go slow and use a light touch. It doesn’t take much force and by using the drill we can actually grind the screw out of shape. What’s nice is that the circular motion will leave a nice, professional finish to the head. The next to last step is to harden the head by using heat treatment.

I personally find this process to be unnecessary for most of our repairs, but if you are interested I advise you to purchase some Brownells Hard-N-Tuff Steel Hardening Compound. Mine came with easy to follow instructions and there are many treatises on heattreating metal available to the scholar both in print and on-line. I say the next to last step because the final thing we need to do is reblue or re-brown the screwhead to match it to the appropriate firearm.

I find this easiest to do with a little cold blue or brown. If working on a high-dollar piece or trying to absolutely match the other screws on your job, I refer you to the many references on refinishing metal. This is one job where you will find it easy to please your customer when showing the finished product. Where a damaged screw stands out, a repaired one will become invisible. He might have to ask, "Which was the one I wanted fixed?" AG