Category Archives: Gunsmithing

Sixgun Flu

Fine-tuning the double-action revolver.

Most box-stock autoloaders will work pretty well right out of the box fired with the ball ammo most were designed to shoot. Where most go off the rails is with ammo they don’t like. Fed properly, and absent undue wear or abuse, they will soldier on forever. Double-action revolvers, on the other hand, will function with virtually anything that 1) has a live, properly seated primer, 2) fits in the chamber and 3) doesn’t seize in the chamber or blow the gun up on the first shot. But double-action revolvers, especially big bores, seem more prone to get out of kilter through ordinary use and may, occasionally, require some minor adjustments to remain healthy and happy.

While these remarks are generally applicable to all DA revolvers, they are specifically tailored to the ubiquitous Smith & Wesson guns. There are three major problems that crop up. Typically, the symptoms are the same: the gun develops a ‘gallop’ or cramp in the action cycle that can vary from chamber-to-chamber. In combination, a couple of the problems can bring the cycle to a halt.

Happily, the condition most responsible is the least troublesome to set aright. It is cylinder endfloat, defined as the back and forth movement of the cylinder on the “yoke” in S&W parlance (“crane” in others) along its center axis. In the extreme cases causing action binding, you can almost always hear a click when you move the cylinder back and forth. If you look across the barrel-to-cylinder gap, you can see it tighten and loosen when the action is cycled. If the hand tips the cylinder forward enough to drag on the barrel extension, you will often feel a noticeable increase in cycling pressure. It is not unheard of for the gun to simply stop running mid trigger stroke.

The basic cause is usually just using the gun. The basic S&W design is over a 100 years old and did not contemplate magnum cartridges. The small yoke-to-cylinder bearing area simply batters in time and the increased clearance allows longitudinal cylinder movement. The basic fix it to take up the slack. This is done variously through yoke-stretching procedures or shims. I find the Power Custom shims more predictable. Using as many of the .002″ shims as is necessary, I’ll put them in the bottom of the cylinder yoke bore where the yoke bears and try the cylinder. When it closes stiffly, I know we’re there. I use a Brownells/Power Custom yoke-squaring tool to remove just enough material to let the cylinder run free with no back-and-forth movement. A side benefit is an increased bearing surface once trued up. This should not materially change the headspace but you must check it to be sure. Feeler gauges will do for an open-back cylinder. A recessed head cylinder will require both feeler gauges and depth micrometer. The barrel-to-cylinder gap may show a small increase but usually it remains in spec.

The next adjustment that may be necessary to cure a galloping action is yoke alignment. The cylinder center pin runs in a corresponding hole in the standing breech. If the yoke isn’t in exact alignment with this hole, the center pin will bear on just one side of pinhole and can cause dragging or binding problems, especially if the extractor isn’t well centered in the cylinder. Adjustment is pretty simple and requires a simple yoke alignment gauge and an adjusting tool. With the gun held firmly in a padded vise and the cylinder removed, just install the stripped yoke and yoke side-plate screw, making sure the yoke opens and closes freely. With the alignment tool on the yoke, hold the yoke closed at the front and run the alignment tool nose into the center pinhole in the frame. If the tool won’t go or rubs on an edge, open the yoke, remove the tool and, with the yoke held in the open position by hand, adjust the alignment with a proper adjusting bar by bending the yoke ever so slightly in the required direction. The alignment tool should run freely in and out of the center pinhole.

For reasons known only to the cylinder gods, S&W ejector rods always seem bent or getting ready to be bent. Once tweaked out of alignment, they are another major cause of the dreaded action gallop. Opening the cylinder and spinning it, any serious misalignment in the rod will be evident. With the yoke removed, you will often see a spot of blue wear on a portion of the rod where it runs out and rubs on the yoke. The bigger problem is out at the end of the rod where it engages the front locking bolt under the barrel. This eccentric movement is felt in the action cycle as varying pressure to run the gun from chamber to chamber.

Adjusting the ejector rod alignment is the trickiest part of this exercise and requires dedicated tooling to do it at all well and predictably. The excellent Power Custom ejector alignment fixture isn’t cheap but it works better than anything else we’ve ever tried. The tool consists of a cradle which holds the cylinder assembly and lets you spin it with a dial indicator bearing on the tip of the ejector rod. Again, the adjustment tool is a round bar with a hole in it to accept the rod. Once you determine the direction of the misalignment, you tweak the rod the other way. Sounds easy enough in theory but, in practice, it can be a bit exasperating and can take a few minutes of fussing around to perfect. We figure anything less than .005″ or so is about as good as it gets.

This general malady is fairly common and is regular fare for revolver doctors. The condition rarely disables a good revolver but leaves it in a miserable, sickly state. Unlike a lot of basic gunsmithing, unless you have the tools, there may be no substitute for seeking professional help. Still, just recognizing the symptoms will give revolver shooters a fighting chance of curing revolver flu.
By Hamilton S. Bowen

Grand Masters LLC
(Formerly Power Custom)
29379 Hwy. J, Gravois Mills, MO 65037
(573) 372-5684

200 S. Front St., Montezuma, IA 50171
(800) 741-0015

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October Guns 2012

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Measuring Tools

They’re Needed For Many Shooting Endeavors

Believe it or not, human beings do not think about sex every waking moment. The other 10 percent of our contemplative time is given over to pondering topics like money, margaritas, why we are here or, in some rare cases, the physical characteristics of our world. For gun junkies, that world encompasses a lot of speculation on height, width, diameter, distance, various spatial relationships, etc. We’ll contemplate here a few of the necessary tools useful in the satisfaction of our curiosity.

You do not have to be a practicing gunsmith to need measuring tools. Shooters are always measuring group sizes, hole spaces for scope mounts of peep sights, length of pull and so on. If you are a reloader, then you are constantly measuring case lengths, bullet diameters, head diameters, case wall thickness and the like. How sophisticated your tools are depends on the job to hand. Measuring cartridge case length with a plastic caliper is fine. Measuring case head expansion for pressure signs requires a high-quality blade micrometer graduated in .0001″ increments.

Micrometers are the most accurate hand measuring tools we mortals can buy. The better ones will measure precisely, repeatably in .0001″ increments. Since more precise measurements are an indicator of importance, this is one place not to scrimp on quality. You get exactly what you pay for so expect to pay $100 to $200 for a good one. If you procure only one, the standard 0-1″ with flat anvil and spindle faces is the most important. While digital tools are now all the vogue, there is something inelegant about them that leaves me cold and uninspired. I like pretty stuff, including tools.

Alas, not everything can be measured between a couple of flats so micrometers come in a variety of styles. The most important other micrometer for use around a gun shop or the reloading bench is the tubing micrometer which has ball anvil and a flat spindle for measuring tube wall thickness or hole distances from edges. Their obvious lower limit on measurements is governed by ball diameter. I use mine regularly to measure cartridge case wall thickness. Another helpful specialty micrometer is the blade type for measuring into narrow spaces like grooves or slots. Mine has been used more for measuring cartridge case web expansion at the head in search of pressure-related changes. Depth micrometers are critical for measuring and setting headspace when re-barreling a rifle.
By Hamilton S. Bowen

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Installing A Rifle Scope

It’s Not Hard, And A Few Good Tools Help.

Hunting season is not far off and, naturally, all we nimrods will start pondering our choice of weaponry. Some of us will take old favorites. Others will start afresh. Many of the others will want to apply a scope to their new piece. Thanks to the enormous technical resources available to modern hunters, it is simple and any hunter who can field dress a deer can handle a scope installation. We’ll assume you have a typical bolt-action rifle but what follows is applicable to most any rifle. At the expense of belaboring the obvious, make sure the gun is unloaded and no ammo is anywhere nearby.

Once you have your rifle in-hand, decide on a scope. This brief treatise must necessarily confine itself to the installation rather the optics selection but, that said, I will offer one piece of advice. The tendency is to procure scopes of unnecessarily high magnification. All the scope does is provide a more precise sighting picture by putting all sighting elements on one clear plane. It is not a spotting device. All you need is a reticle you can see and place on the kill zone with a little room left over. You don’t need to fill the view through the scope with deer since you then restrict the all-important field of view. I want to see not only the deer but a lot of his surroundings so I can figure out what to do next if something goes off the rails. You can make a grizzly bear out of a prairie dog with a powerful enough scope—if you can find him in the first place.
By Hamilton S. Bowen

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The Final Touch

Firearms Markings

Within most professions in this world, despite the best efforts of professional organizations and sanctioning bodies to achieve uniform standards of performance, there are often great discrepancies in skill and ability of members. In many cases, these differences of skill and talent are inconsequential. In others, say, for instance, brain surgery, you would like to think everybody out there practicing the craft is equally and supremely competent. In the world of the arts, manual and otherwise, these variations are not usually life threatening but merely reflect on the general skill level of the practitioners.

So it is with lettering from gun makers, custom and production alike. Some of us get downright persnickety about lettering while others have a more relaxed “Git ’er done” attitude. In my humble opinion, proper markings on receivers and barrels can make all the difference in the world, distinguishing stylish from otherwise indifferently rendered pieces of work. We’ll take a look at some examples of lettering and contemplate available technology.

If you think about it for even a moment, you can imagine the difficulty or producing a stamping die. In the olden days, before photo etching, EDM (electro discharge machining) and N/C (computer-driven) technology arrived, roll marking dies were laboriously carved by hand in steel by engravers of otherworldly skill. In reverse. Or worse, in-the-round to follow a barrel contour precisely. Not surprisingly, these stamping dies were goofy expensive and used exclusively by major manufacturers who could amortize costs over tens of thousands of units of production.
Story By: Hamilton S. Bowen

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The Crowning Act

Some years ago, the shop had completed a nice little Old Model Ruger revolver caliber conversion with dedicated .44 Russian chambers. If ever a gun should have shot well, this should have been it. Alas, on the first trip to the range, I would have been lucky to hit myself in the foot. There was no accounting for the awful accuracy. The rebore from Delta Gun Shop look great. It ranged perfectly. The forcing cone was in spec. Our reamer had a throat section of around .430″ which was spot on. Factory ammunition from Black Hills admitted no problems. I simply could not figure out why this gun shot so poorly. Giving it yet another hard look and thinking to myself the muzzle looked a bit odd, it finally dawned on me I had not yet crowned the barrel.

Ordinarily, most modern firearms feature precisely machined crowns that rarely ever give trouble, but the Ruger barrel had just been rebored and the bullets were now emerging from a flat crown that showed the usual ground/polished crown of the times. Without the usual 60-degree inner chamfer that trued up this surface, the remaining flat crown was hopelessly out of square and gave the predictably awful results.  The moral of the story is simple: When all else fails, check the crown.

A barrel’s crown is a small thing, but a poorly executed crown on any rifled barrel will have a devastating effect on accuracy. While I do not profess to have a thorough understanding of the dynamics of bullets exiting barrels, it requires little mental heavy lifting to recognize the problem. If the entire circumference of the heel of a bullet doesn’t exit the barrel at exactly the same time, subtle variations in gas pressure bearing on the bullet’s base and pressure from the barrel itself on the bearing area of the bullet can cause the bullet to tip slightly off its axis when it exists the barrel. Once tipped, the bullet will tend to wander off course more than usual. In short, the crown must be as square as possible with the bore axis.

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The Smartest Man I Know

And Why Everybody Needs To Know One

When most of us ponder gunsmithing shops, we conjure up visions of a building chock full of machines, tools, fixtures, vats of unappealing liquids, hoppers of gun parts, corners occupied by stands with firearms in various states of disrepair, and maybe a poster or two of some guns up on the wall. Out of this physical plant emerges the finished product, typically produced along the lines of sausage—which nobody should ever watch done. While it is true physical resources are critical to the proprietor’s success, his human resources are just as important, because without them the enterprise will surely fail.

No matter how smart your pet gunsmith is, he will inevitably encounter problems that are simply insurmountable with his equipment and skill. No amount of study of manual or gunsmithing text will get you through some difficulties with uncooperative guns, tools or processes. What separates the men from the boys is the wisdom to recognize their limitations, and have written by the phone the numbers of vital human resources to call upon in time of crisis.

I may not be the brightest star in the firmament but my momma didn’t raise no fool, so I have spent a lifetime accumulating friends who are sources of skills, gear and knowledge which I do not have. You should, too. My gang has done a lot of bacon saving during my career. I’ll tell about a few of them but you can’t have their phone numbers; some names have been changed to protect the guilty and innocent alike.

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Installing A Rifle Trigger

Some Guns Are Pretty Easy, Some Aren’t

Thanks to the depredations of the tort bar, firearms manufacturers have been forced to make their production handiwork ever safer by dumbing down trigger quality, and hiking up pull weights and sear engagement. True, cost plays a certain part in trigger-pull quality but most of us would pay a little extra to have a safe trigger for our favorite Winchester or Ruger bolt-action, big-game rifle that didn’t feel like a Glock trigger lubricated with sand.

Luckily, there is help in the form of aftermarket parts. Just peruse the Brownells catalog and, chances are, you will find a trigger (or several) for your favorite rifle that you can install with a few simple tools on a quiet Saturday morning. Some triggers are quite complicated and must be installed by an experienced gunsmith, such as most anything that requires machine work. Ruger No. 1, Remington 700 and M98 Mauser double-set triggers are probably beyond the ken of most hobbyists. On the other hand, many Ruger, Winchester M70 and AR-15 triggers are near drop-in and really require only disassembly and reassembly to install. Many have a fair range of adjustments lacking on factory units and will yield-surprising improvements in trigger-pull weight, felt creep and over travel without recourse to spending the week’s beer money.

For example, the shop’s safe yielded a couple of likely victims on which to demonstrate—a seedy Ruger 10/22 .22 semi-auto kept to repel varmints, and a handy M77/44 .44 Magnum bolt-action carbine. As always, it is well to lay hands on some sort of disassembly guide if you are not familiar with the entrails of your gun. Though most bolt-gun trigger work requires the simple removal of barreled actions from the stocks, some autoloaders may have action disassembly. My greasy, dog-eared disassembly guides written by J.B. Wood will usually have the information needed to get me through.

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New Life

The Art Of Barrel Reboring

Barrel reboring is one of those obscure but vital services to the gun trade that gives life to all manner of restoration, repair and custom gunmaking projects. This short column will hardly do the subject justice but it is important just to touch on it. Reboring, as opposed to making a rifled tube from scratch, is simply removing existing rifling and cutting new rifling in a larger caliber. Believe me, use of the word “simply” is highly misleading because the process is a complicated art that takes a lifetime to master. Which is why, important as it is, there are few successful practitioners.

The reboring process is simple in theory but equipment-rich and heavily nuanced, requiring a sophisticated understanding of machine-tool processes. A barrel is fixtured on a lathe-like machine. Then, a piloted counter-bore (a guided, square-ended drill) is run into the barrel to remove the bulk of the material between the existing bore and the new rifling.

To smooth this cut and bring it to final size, an unpiloted reamer is run through next. At this point, reborers may hand lap the barrel, a precision polishing process to smooth out imperfections and tool marks and to ascertain a consistent bore diameter all the way through—critical to good accuracy in a barrel.

Last, the tube is rifled with a special cutting head with an adjustable cutter. Multiple small, progressively deeper cuts are made until the target groove depth is achieved. The last step is to lap the finished product. The process may involve two or three precision machines with high-pressure tool lubrication systems and countless bits of specialized tooling in the form of reamers and cutters, each dedicated to a specific caliber.

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June 2011

April 2011


Milling Machines For The Masses

When civilians think of custom gunmaking shops, many see buildings bulging with lathes, milling machines, jig borers, surface grinders and the like. Indeed, many do but in serious gunsmithies, the humble file is still the most important metalworking machine in the place. For some jobs, there is no substitute in terms of speed, handiness and flexibility. A few hundred words will barely scratch the surface of the subject of files, but we’ll cover some basics for home craftsmen.

As always, the MSC catalog will have an excellent primer on most any machine-tool subject. Files are no exception. If you do not already have this catalog, you owe it to yourself to lay hands on one, not only for the wealth of useful tools for sale but also for the excellent technical descriptions and discussion of their uses. The Brownells catalog is another source and will often have dedicated gunsmithing files not available in mainstream suppliers.

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April 2011

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Accurizing The Factory Ruger

10/22 Rifle

A Little Trick Does The Trick

Introduced in 1964, Ruger’s 10/22 autoloading rifle is one of the most popular members of the rimfire genre ever. No greater compliment is paid these well-engineered guns than the cottage industries that spring up yearly making accessories and performance parts. Despite all the available upgrades-in-a-box, some of us like doing our own work. The 10/22 is amenable to many simple do-it-yourself modifications.

My sporter model was reasonably accurate but not spectacular. Rather than purchase a new barrel, I elected to see if improved accuracy would be obtained simply from better chamber throat specifications and better headspacing. Many others have written well, and in great detail, before about such modifications but they bear repeating here.

Most .22 target arms are chambered with dedicated match-spec reamers, with shorter chamber body and throat sections than the standard “sporting” chambers. While more finicky about ammo and function, the match chambers center cartridges and minimizes bullet jump to the rifling, thereby improving relative accuracy. My reamer is of the popular “Bentz” pattern and came from Manson Precision Reamers. The body section is about .100″ shorter than the standard chambers.

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Feb 2011

Dec 2010