Learn from the misfortunes of others to avoid making these gunsmithing mistakes when repairing or maintaining your own firearms.

Mistakes in gunsmithing fall into two categories. There are those you can fix with money or effort, and those that require paperwork. Both happen because you didn’t apply patience. Before you tighten the vise and begin cutting, drilling and filing, or fire up the torch, think through what you’re going to do. A moment spent visualizing can save you a lot of hassle and hours, days or even weeks of work.

Don’t Work On Irreplaceable Firearms

Do not work on irreplaceable guns unless you are a pro and you’re willing and able to replace them if you screw up. If someone comes to you with a Jim Hoag or a Swensen–built 1911 and wants you to replace knarfed grip screws, go for it. Find some as close to original as possible and replace them. If they want you to refinish it, replace the barrel or checker the frame, counsel them that they are trying to irrevocably alter a historical, valuable collectible, and they shouldn’t do it … and you won’t!

Something like a pristine WWII bring-back should be cleaned, carefully, and left as-is. Some things should be left alone.

Don’t go increasing power on something. If someone approaches you at the gun club, knowing you do pistolsmithing, and wants you to take their old S&W M-28 and re-build it to a .44 magnum, turn them down. First of all, S&W won’t sell you the magnum parts. Second, there’s a reason they make new .44s, and don’t re-build old guns to new, bigger calibers.

A Union Switch & Signal 1911A1 is much more valuable as a collectible than anything you can do to make it a world-beating competition gun. In fact, the owner could sell it for enough to buy a matched pair of custom-built 1911s, and have two more-durable guns to boot.

1942 Singer Gunsmithing-0014
This pistol, an original and unmolested Singer from 1942, is far too valuable to change anything. Leave it alone and find something else to practice on.

General Considerations

Don’t make a change that can’t be reversed for a competition gun unless you’re sure it’s an allowed modification for the discipline in which you plan to shoot.

Hunting regulations matter. My .40 Super is a very good selection for deer hunting, except for a pesky part of the Michigan regulations: The handgun-allowed areas specifically disallow bottlenecked cartridges.

You may also have to take into consideration bizarre state or national laws. You may live in a state that insists on sample bullets as a requirement of sale. Changing barrels might also require a sample bullet. It may require a sample bullet from a “certified testing laboratory” or someone certified, bonded, inspected or approved. Make sure you know what is allowed.

The Loctite Episodes

Some thread-locking compounds fix quickly. One of the fastest setting is my favorite, 680 Shaft and Bearing, the dark green stuff. It fixes in the absence of oxygen and when friction stops. You can keep turning the part while 680 is on the threads and it won’t set up, but don’t stop.

Loctite wicks. Every gunsmith in the country has bonded a trigger assembly together at least once. Once it starts wicking you cannot control where it goes. Use it sparingly, and use gravity to control it. Then check everything again after the Loctite has set. I once had to chip the Loctite off a rifle trigger mechanism (and detail strip it to do so) from an errant few drops of Loctite that were meant to keep scope mounts in place.

Loctite does not work through oil. My first few scope mounting jobs came loose because I did not sufficiently degrease the threads. I thought I had, but what seemed good was not what the real world said was good. If you plan to use Loctite, degrease the threads.

Parts Is Not Parts

Keep track of what you’re doing. Work on one firearm at a time. I once had a customer come in with his fully tricked out, super-custom competition 1911 that had suddenly “lost its accuracy.” I was puzzled at first, but upon inspecting it discovered that the barrel was a loose fit. I stripped it and looked underneath, and sure enough the barrel was marked with a different serial number than the frame and slide. (Many custom gunsmiths number-match major and minor parts to each gun to make sure they don’t get misplaced.) The barrel in his custom gun was the barrel from his carry gun. The match barrel was such a tight fit in his carry gun (which he had on at the time) that it would short-stroke if fired. He had decided to clean them both the weekend before – at the same time – and mixed up the barrels upon reassembling them. Luckily, he’d gone for practice with the competition gun before he needed the carry gun at work.

If you own identical firearms and are in the habit of working on them at the same time, it might not be a bad idea to get an electric marking pencil and mark the last two, three or four digits of each of their serial numbers in unobtrusive places.

We all know about poor-quality magazines, but there are other parts that can be poor quality too. Like the fellow who invested in a cheap replacement barrel at a gun show for his 1911. Too bad the barrel was made of soft steel and the locking lugs on the barrel peened. Once they’d peened enough, they started chipping the locking lugs on the slide. The end result of “saving” $50 at the gun show was a new slide and barrel, and the labor to fit them – about six times the price.

Rare Nambu Gunsmithng-0152
This is a baby Nambu. Rare hardly begins to describe it, and it is off limits as far as gunsmithing modifications are concerned.

Milling And Drilling

Is the location you’re about to drill the real, actual, place you want that hole to be? Once drilled it is difficult to re-drill. Yes, you can tap the hole, secure a threaded plug in place and re-drill, but even then there can be problems. What if the new plug you just laboriously installed is a different hardness than the surrounding metal? The correct, offset hole may wander when drilled. The plugged hole may show after you’ve installed whatever the part is.

A gunsmith of my acquaintance once did not secure the dovetail cutter tightly enough in the chuck before proceeding to mill the dovetail slot in a slide. The force of cutting pulled the cutter down out of the collet and into the slide as it fed across. He was halfway across the slide before he noticed. Luckily the customer wanted the slide hard-chromed after all the work was to be done on his expensive and super-custom 1911. The solution was to file a piece of steel to fit in the mutant sight dovetail. Then solder it in place, machine the slide correctly, finish filing the edges of the plug to match the slide, then machining French borders to hide the plug, polish, bead-blast and plate. The customer loved it and showed all his friends the extra work he’d gotten as a make-up for the delay in delivery. The gunsmith ended up spending an extra five hours of time on the job because he failed to spend 30 seconds making sure everything was tight and correctly positioned.

Then there was my “oops.” I drilled a scope mount on a rifle and “kissed” the barrel threads. (I mis-measured the stop gauge on the drill press by .010 inch.) No problem, as the customer never intended to change the barrel. Well, you guessed it. That hunting season was a very snowy one. His muzzle ended up in the snow, he split the muzzle on firing it, and he wanted a new barrel. I had a heck of a time getting the old barrel off, what with the drilling burrs I had created. It turned out all right, but I spent an extra week soaking the threads in Kroil, and took a lot longer to clean the receiver, rosin the surface and clamp it as tight as I could make it. I crossed my fingers before going to unscrew the barrel.

Parts Is Parts

If at all possible, do your filing, stoning, fitting and other work on a cheaper or more easily replaced part. Sometimes you can’t avoid it. You must cut the frame to fit a beavertail grip safety. But if you need to fit a bushing on a 1911, fit the bushing and don’t go cutting on the barrel or slide if you can avoid it. If your trigger is too large to fit the 1911 frame, file the trigger and not the frame.

Practice fitting on old parts bought for the purpose. Improving your trigger by stoning the sear that came with it goes much easier if you practice beforehand on one bought at a gun show for a dollar. Buy a rusted or busted barrel and have it welded up to learn how to fit barrels. That’s also the way to let your welder get some practice, although don’t be surprised if he charges you for it. Unless you’re a working gunsmith you won’t have the luxury of practice guns to work on, but old parts are cheap, and bar and round steel is cheaper still. Practice takes time, and if you are working for yourself, time doesn’t matter. A pro has to bill his time, and practice is time he can’t bill (but a necessity regardless of cost). You aren’t billing your time and are working on your own handguns. Get it done right by working your mistakes out and building your skills on practice parts.

And if you do make a mistake on a “good” part, don’t be cheap. So you stoned a Chip McCormick sear to death? Or a Wilson? Spend the less-than-twenty bucks and buy a new one and learn from your mistake.

The Early Plate Job

Hold off getting your gun finished, especially if you are a competition shooter. You may find that there is a sharp edge or corner you hadn’t noticed at first. Or the safety chafes once you’ve practiced with it. Or the sights just aren’t all you’d hoped they’d be. But now the plating you so eagerly had applied has to come off before you can get the extra work done.

Most plating cannot be treated like paint, that is, “spot-sanded” and retouched. It all must come off. The plater will charge you to remove all of the old and charge you again to plate anew. If you want to shoot your new custom gun for a while before getting it plated, you can have it blued. Or you can treat it to a bake-on finish from Brownells. The finish will last long enough to let you determine that you are ready for plating. The temporary finish will also protect the surface until you can have it finish-polished and plated.

One aspect of plating you need not worry about: porting. Chrome, nickel and other metal platings are all electrically conductive. Mag-na-port will not have any problem porting your barrel (or slide) through the exterior plating. If you have a non-conducting finish like a bake-on epoxy, they can scrape enough of the finish off for the electrodes to find a conducting surface to work with, and then port through your finish. But the final finish will be better served if you port first, then finish.

Gunsmithing Mistakes-0772
This gentleman knows exactly what he’s doing, so the stream of sparks is not cause for alarm. If you are getting ready to grind, cut, file or machine, remember: measure twice, cut once.

Paperwork Errors

There was a fellow who was so taken with the idea of turning his old surplus M-1917 S&W .45 ACP revolver into a snubbie that he didn’t measure the location of the serial number. Taking square-butt revolvers and turning them into round-butt revolvers was something that used to be done a lot more often. The factories had made a bazillion square-butt wheelguns, and buying a new, round-butt revo could be expensive.

He used a pair of round-butt wooden grips as his grinding template and ground the backstrap and butt to match the grips. Only when he went to have it polished for bluing did he discover he was missing a digit and a half from the serial number. Luckily for him, the serial number was also stamped on the frame in the crane cutout. However, even with a pre-existing, valid serial number in place on the gun in a different location, it is a technical violation of Federal law to alter or obscure a serial number. Learn from his lesson.

One prospective paperwork error is the crushed frame. If you attempt to clamp your pistol frame in the vise without a clamping block in place, you may crush the frame. It is very difficult to restore the interior to a size that will accept a magazine. If you are lucky, the factory will replace the frame with a new one bearing the same serial number (and destroy the old one). They will charge you dearly for it. If they cannot or will not send it back bearing the same serial number, you must then go through the paperwork process of proving the old one scrapped and then registering your “new” firearm. The simplest way to do so is to turn it over to a professional gunsmith and his Federal Firearm License. He can enter the old one on his books, then show it sent to the factory and retained by them. You then keep the work order showing the disposition of your “old” firearm. You “purchase” your “new” firearm from him, conforming to all the state requirements. All in all an expensive lesson.

The prospect of replacing a busted frame with one of the same serial number is now not as easy as it used to be. I was discussing the subject with a big manufacturer, and had the following story related to me: apparently manufactures get regular government inspections. On one of these, the ATFE agent being escorted around passed a door and asked “What’s in there?” Answer: “Oh, that’s where we keep the un-numbered frames for repairs.”

Not anymore, they don’t. Now, if that company wants to replace your frame with one of the same serial number, they have to have an employee intercept a correct frame at the serial-numbering station, pluck it out of the production stream, then walk it to the custom shop, where it is stamped with your gun’s number right after the frame of your gun is destroyed. That’s a lot more cost, and may mean the end of the courtesy of same-numbered replacements. And when it happened, it was just that, a courtesy.

Getting Hurt

Back in junior high school shop class my teacher was Mr. Braisted. One of the items on his desk was a looseleaf folder full of photographs. Some in color, most in black and white. They showed the injuries suffered by people who didn’t pay attention to safety. The one that sticks in my mind was the guy who was using a file on a lathe-turned part to polish it. He neglected to put a handle on the file and, when the file got snagged by a jaw of the chuck, it impaled his hand with the file tang.

In our own class, someone failed to take the drill press key out of the chuck, and when they turned it on the key was hurled off the chuck. It broke the chain and hurled the key across the room, narrowly missing Mr. Braisted.

Those aside, how else can you hurt yourself while pistolsmithing? One way is to forget things are hot. So, you’re soldering a pair of parts, and it slips and you go to catch it. That you’ll only do once. Ditto sharp objects. Wear sturdy shoes, and if something falls, intercept its path with the top of your shoe, to buffer its impact on the concrete.

Never forget the reason firearms exist is to hurl bullets. I was once testing a Browning A5 shotgun in 16 gauge. I chambered a round and pulled the trigger, and it failed to fire. Okay, so I went to pull the charging handle back to unload it and boom!!, off it goes.

The A5 has a safety alignment built into it that if the bolt isn’t fully closed, it won’t fire. Well, the hammer won’t go fully forward. This 16 gauge had been rebuilt from its original 2-9/16” chambering to 2-3/4” and the smith who had done the work hadn’t fully checked his work in also adjusting the hammer clearance. So, chamber a round, pull the trigger and the hammer catches on the action bar. Pull the bolt back slightly, and the hammer clears, goes forward and fires the gun. Because I was careful, the damage was limited to the heavy-duty electrical junction box where the muzzle had been pointed at that moment, and my pride.

Caustic chemicals, flammable solvents, sharp edges, these are all reasons to get in and stay in the habit of dressing for success. That means safety glasses all the time. When the time comes in our law enforcement patrol rifle classes, we tell the officers “wear the safety glasses we told you to bring.” It is amazing how many don’t have such glasses. And even those that do will not always wear them while guns and parts are in play. If you use power tools, earplugs or muffs. A work apron, to keep your clothes clean. Sturdy shoes or boots. And if you are grinding, then a face mask – paper, cloth, respirator, whatever.

Dress properly, and you’ll have a long future of happily working on guns. Fail to dress properly, and things might not be so happy.

Editor’s Note: This article is an excerpt from Gunsmithing Pistols & Revolvers 4th Edition, available now at GunDigestStore.com.


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