The Art Of Accuracy
September 23, 2010
Like any art, and riflemaking is an art, a tremendous amount of work and craftsmanship go into building a precision rifle. Here is an explanation of the process and the approach one custom house takes to produce supremely accurate rifles.
Shortly after the first bullet was propelled toward a target by gunpowder, it is a near certainty the man behind the trigger was thinking of ways to make future shots more accurate. The quest to precisely place bullets at long range has absolutely consumed rifle builders and shooters. Whether the plans were penned with a quill and shaped with a file or drawn up with zeros and ones and executed by a robot, proficiency and accuracy are what define riflemen and rifles. Time has not changed that fact, but technology has made the end result more attainable.
There is not much in the way of hard data to confirm my suspicions of an increase in the number of guys offering up custom work and precision rifles, but it seems, even with my limited perspective in terms of years behind the trigger, that every day someone else hangs out his shingle and declares his rifles the best. With such a proliferation of custom houses, a whole new language has emerged--trued, blueprinted, coated, lapped, and bedded--and we are all quick to toss around the terms. But what do they really mean and is everyone comparing apples to apples? What goes into making a precision rifle?
I was fortunate to meet a gentleman a few years ago that struck me as just the guy to explain the process in detail. Jered Joplin at American Precision Arms has quietly built a stellar reputation for accurate rifles over the past 10 years. Collectively, the guys in his small shop have 45 years of riflemaking experience. APA makes a small line of aftermarket parts and builds everything from benchrest rifles to hunting rifles to rifles for SWAT teams. They handle every step of the process except machining the action from bar stock and putting rifling in the barrel. I liked Joplin's approach, especially after suffering through diatribes from numerous blowhards that proclaim their way is the only way and their rifles are the best, period. Joplin was quick to say there are plenty of great riflemakers, and his processes are time and range proven but certainly not the only way to get the job done.
I spent a day last fall at Joplin's Jefferson, Georgia, shop and looked at all the different tools and techniques that go into building a precision rifle. Joplin first explained that while there are all kinds of rifles, heavy and light, large caliber and small, the principles that go into building an accurate rifle are pretty much the same. APA's craftsmen start with the action.
Every surface of a trued bolt and receiver will be parallel or perpendicular to the receiver's centerline.
All actions are not created equal since rack-grade units could never hope to equal the precision or consistency of a custom action from companies such as Nesika or BAT Machine. They also do not cost more than a grand.
Regardless of where it comes from, each action gets a thorough inspection by APA's craftsmen, who carefully measure critical dimensions. The process is commonly called truing or blueprinting. Blueprinting, in its truest form, would involve matching every critical measurement to a set of drawings, which no one does. Truing simply assures that all the angles are square or perpendicular to one another and other parts are perfectly concentric. While used interchangeably, the two terms really mean different things.
"We measure every component to make sure it's perfect," Joplin said. "There are no guarantees, and nothing is taken for granted, since we've seen 'custom actions' that were out of square. Nesika and BAT have proven phenomenal over the years--their actions are right."
A depth micrometer is used to measure from the receiver face to the boltface to determine headspace after truing. In addition to checking consistency, the measurements will also determine how the barrel is machined. The rear contact surface of this bolt lug has been lapped into the lug seats. With both lugs lapped, the cartridge does not move when the rifle fires, and the bullet enters the throat perfectly straight.
I have seen truing and blueprinting offered as a service for the princely sum of $75. Should you encounter the same "gunsmith" or "custom rifle builder," run like hell since no reputable outfit could afford to do a proper job for that much money. Some guys call whacking off the receiver face square to the action body truing when the operation is really much more involved. The operation, depending on how out-of-spec the action is before the work begins, usually takes around two to three hours.
Joplin walked me through the steps using the most common action on which custom rifles are built--no surprise here--the Remington Model 700. Since the action is round and the bolt is round and there are no strange cuts for bolt stops, extractors, or leaf springs to power an extractor, getting things true is fairly simple. Every measurement starts from the action's centerline, and there are lots of ways to find the centerline.
"On a Remington 700, the receiver face is cut perpendicular to the action's centerline," Joplin said. "Then the barrel threads and lug seats are cleaned up and the bolt lugs are lapped into the receiver. The boltface is also cut square to the receiver face. We are trying to get everything either perpendicular or parallel to one another to within a few ten-thousandths (.0001) of an inch. That is the goal."
How does Joplin arrive at what to cut where? He does it through very careful and continuous measurements throughout the process. A professional-grade set of measuring tools on the workbench is the first clue your riflemaker has a clue.
"We measure from the receiver face down to the lug seats from multiple locations, from 6 to 12 o'clock and then at 3 and 9 o'clock, to make sure things are square," Joplin said. "After the bolt lugs are lapped, which is the last step, we measure from the receiver face to the boltface to make sure they are consistent."
When metal must be removed, it has to be done very carefully and in the smallest of increments. An extra thousandth here or there could scrap an action.
not hogging out huge amounts of metal here," Joplin said. "This operation has little or no effect on the way the bolt locks up inside the receiver and certainly doesn't reduce any inherent strength."
The goal is to get the bullet headed into the barrel as straight as possible and make the entire rifle ring like a tuning fork when powder starts to burn. Since it all starts in the action, it is critical that the action is perfect. The vibration, or more importantly the consistency of the vibration, that travels up and down the rifle when fired has a huge impact on accuracy.
"It all boils down to harmonics," Joplin said. "If there is a stress point or bad spot when the rifle is assembled, you will get inconsistent harmonics and a decrease in accuracy. Assuming the bullet is running at the right speed and at the right twist rate, the action should provide a harmonically stable platform so that the bolt does not torque and the barrel isn't canting. Lug contact is a great example. If one lug has more contact than the other, it can cause the bolt to cant towards the weak side when the rifle fires. That would torque the cartridge and send a bullet into the rifling off square."
Joplin measures bolt nose recesses for length and width to make sure the bolt gets at least 0.10 inch clearance and does not touch the barrel at any point. While APA has a proprietary set-up process, many riflemakers set up their lathes like this to machine a rifle barrel.
A live center finds the bore's centerline for precise, concentric machine work. The barrel's outside diameter should never be used as a starting point. The bedding process creates a precise reverse of the action's footprint to relieve any firing stresses. An aluminum pillar is set into the stock at the same time and prevents the action screws from pinching or crushing the stock.
It would be easy to devote this entire magazine to the art of barrelmaking. Heck, if every magazine this year were devoted to the subject, the surface would barely be scratched. It is a black art that has driven men mad, and Joplin prefers to buy rifled and contoured blanks from established companies and preserve his sanity. While some custom houses do produce their own barrels, they are usually barrelmakers first and rifle builders second. The business is just that crazy.
The first step of the two- to three-hour operation is to turn down and thread the breech area. Cuts for the bolt nose recesses follow--no part of the bolt should touch the barrel. The chamber is then cut and checked for headspacing. Finally, Joplin cuts the crown and/or threads the muzzle for a brake or suppressor. The first step to successful barrel machining is indexing the lathe against the bore's centerline, not the outside diameter.
"You absolutely have to machine the barrel in a manner that lines up on the bore's true center, never on the outside diameter, otherwise the hole would not be perfectly concentric with the outside of the barrel," Joplin said. "Also, we want our chambers to only have a few ten-thousandths of runout."
Once threaded and chambered, the barrel can be mated with a trued action. Torque ratings vary widely throughout the industry. APA likes 100 foot-pounds of torque, a slight crush fit, on hunting and tactical rifles. A benchrest shooter that switches barrels after just a couple thousand rounds might specify just 40 ft-lbs. The joining of barrel and action, obviously, is a critical operation.
Joplin drops the finished action into a stock and secures it with 55 to 65 inch-pounds of torque.
"There is a fit and feel to the process," Joplin said. "You know what good threads feel like when assembling the parts. And you can't learn this from a book; it takes years. You have to be more than a lathe monkey; it's a craft."
It is pretty obvious that to shoot accurately, you must address or hold the stock correctly. The same goes for the way the stock addresses the action and how it handles the recoil generated by firing. The good news is that science has provided stockmakers with materials impervious to everything but unskilled rifle builders armed with milling machines and drill presses. Bedding an action takes around three days--the busy work only takes an hour or so--since the bedding epoxies must completely harden before firing commences.
Joplin first checks that the barrel has the right clearance. Old-school guys used to bed the barrel along its entire length. Now most guys completely free-float the barrel up to the recoil lug to eliminate the chance that the stock might produce the slightest pressure or change vibrations. Joplin carefully removes a small amount of stock material around the entire action's length and recoil lug. Wet epoxy is put into the stock, and the barreled action, taped up or coated with a release agent, is dropped into the stock and tensioned into place. The excess epoxy is removed, and the rifle is set aside until the new footprint sets.
"A bedding job eliminates stress on the action," Joplin said. "It looks simple, but it's an easy way to mess up a rifle's accuracy potential. It has to be done correctly."
Every complete rifle build is checked on a nearby range for accuracy. APA guarantees half-MOA with match-grade ammo.
Joplin likes adding aluminum bedding pillars to the stock, though he is quick to say it is possible to build an accurate rifle without them. Machined in-house from aluminum stock, most measure 9/16 inch. F-Class rifles get 3/4-inch stainless-steel pillars. Radial and lateral grooves are machined into the pillar surface to prevent movement in the stock. The pillars are attached with the action screws and set into the epoxy at the same time as the action. Then the bottom metal is bedded to the stock. The two-part process takes more time but is more precise.
"We use aluminum pillars about 90 percent of the time to control the amount of torque applied by the action screws over a broad range of temperatures," Joplin said. "We also make sure the barrel and action are not canted at an upward or downward angle. There are not a lot of fancy measurements here; it's mos
tly eyeball work."
There is a simple layman's test to see if the stock is placing undue, accuracy-killing pressure on the action. First, stand the gun up on end with the recoil pad down on the ground. Place your index finger where the barrel and stock meet. Loosen the front action screw and see if the barrel moves. If it does, the action is stressed, and you might have accuracy problems as a result.
"You are looking to create a stress-free footprint of that action in the stock," Joplin said. "If there is something wrong in the stock or bedding, the gun will never reach its potential. Actually, quite a lot of work goes into making the stock right."
Besides the absolute care and precision with which parts are made and assembled, it is the quality-control checks at the end of the build process that separates a true custom rifle from rack-grade or production custom guns.
Throughout the build, individual parts are checked after machining and checked again for function with surrounding parts when assembled. The trigger--APA likes custom units from Huber Concepts, Jewel, and CG Jackson--is measured for consistency. Scope bases are carefully installed, and the rings are lapped.
"Our inspection is two pages long, single spaced, and nothing leaves here unless it goes through this check," Joplin said. "Like an airplane, the rifle doesn't leave the ground. It takes time, slows us down, and costs the customer more money, but it is what guarantees consistent accuracy, and that keeps the customer happy."
Rounds are fed through the action to check for feeding and extraction hiccups. Most factories function check their rifles with a few rounds and occasionally lot-test them for accuracy, but testing every rifle is usually out of the question. A production supervisor at a major manufacturer once told me that accuracy testing every rifle would add $75 to $100 to the retail price. APA has access to a private, 700-yard range and test-fires every complete rifle with match-grade ammunition from CorBon, Federal, and Black Hills.
"This is the crucial part of the process since our rifles are guaranteed to shoot half-MOA," Joplin said. "It's the only way we can ensure a rifle is 100 percent, and we want our customers to be satisfied in every way."
The final step is putting a finish on the metal and stock if specified. A balance between cost, durability, ease of maintenance, and attractiveness must be struck, and the decision really depends on how the end user intends to apply the rifle. If there was the perfect coating, shooters would have found it years ago. APA does all its own finish work in-house using everything from Cerakote to standard mil-spec Parkerizing. Joplin's rifle builders have spent hours perfecting their mixtures and application techniques. Applying the finish usually only takes an hour or so, but cure times can run three or four days.
Delivering The Goods
Assuming all the parts were in-house and a guy had just one rifle to build, the entire process would take a couple of days, not counting drying time. So why does it take most custom houses five or six months to deliver a rifle? Barrels are one of the biggest log jams. Most good barrelmakers stay months behind since near-perfect barrels simply cannot be rushed. Only a small percentage of custom rifle work can be accomplished without the barrel attached, so quite a few riflemakers have trays full of ready-to-go actions waiting on barrels. Stocks that match custom actions are often hand-built affairs, and most stockmakers set up their production runs in batches. So it can be several months before your favorite stockmaker gets around to making Surgeon- or Nesika- or BAT-compatible stocks.
A completed rifle can only be as good as the sum of its parts, so the higher quality components that go into the rifle, in theory, the more accurate it should be. That is true to a degree, but the way the rifle is assembled is the only way those components will ever realize their full potential. This is where the skills of the riflemaker come into play. Joplin was quick to say the occasional factory rifle will drive tacks, and less skilled riflemakers can turn out extremely accurate rifles. What moves a craftsman into the upper echelon is his ability to produce rifles that always shoot under any condition."The difference in a good gun and a great gun is in the small details," Joplin said. "When you guarantee your rifle to shoot half-MOA, every little part, every process, every machining step demands perfection."
It is Joplin's undivided attention throughout the process that demands the high prices paid for an American Precision Arms rifle--complete builds start at $1,750. A few factory rifles will shoot as good as one of Joplin's rifles, but every gun wearing the APA logo, or the logo from any competent and conscientious riflemaker for that matter, will always shoot.
Hopefully this walk through a custom rifle build will give you a better idea of the terms used, the time it takes to build a precision instrument, and the exacting nature of the work.
Contact American Precision Arms at 706-534-1577.