Secrets Of Accuracy
September 23, 2010
Here's what it takes to get minute-of-angle accuracy or better in your rifle
When I first started writing for the outdoor magazines some 30 years ago, a rifle that would consistently shoot groups of a minute of angle or better were as scarce as turkey lips. Rifles capable of 1.5-inch groups at 100 yards were considered to be very accurate shooters, and two-inch groups were acceptable to most hunters.
My colleagues who owned such rarities as MOA-capable rifles wrote about them in glowing terms. Many other gunwriters, including the dean of them all, Jack O'Connor, often belittled the stories of super-accurate rifles as occurring far more often in the typewriter than on the range. I can recall writing a piece that I called "The Accuracy Myth" about 25 years ago in which I came to about the same conclusion. I had owned quite a few rifles, and only a handful would consistently deliver MOA-or-better groups.
However, gunmakers--both factory and custom--have learned a lot about accuracy and how to achieve it in the years since. These days, MOA-capable rifles and shooters are not at all uncommon. In fact, several hunting rifles in my present battery will consistently deliver half-minute groups if I do my part.
We still don't know all the secrets to gilt-edged accuracy; if we did there would be no inaccurate rifles. However, we seem to be closing in on solving the mystery.
There are several major contributors to accuracy in a rifle or lack thereof. The first and probably most important factor has nothing to do with the rifle but rather the ability of the shooter. No matter if the rifle is capable of consistent one-hole groups, if the best the shooter can do is two or three MOA, then that is the best that can be produced at the range.
The second most important factor is the quality of the barrel. After that is the concentricity of the action and the quality of the trigger. Next comes the stock and the bedding of the metal to wood (or fiberglass or laminates). The precision and durability of the sights are very important, and finally, the quality and consistency of the ammunition are critical.
It is pretty easy to discover the ability of the shooter. Simply take a rifle-and-ammo combination of known accuracy, and let the suspect shooter have at it on the range. Either that or get a shooter of demonstrated ability to shoot a questionable rifle. Either way, it will quickly be shown if the shooter or the rifle has the major problem. However, no shooter is capable of producing super-tight groups all the time, so no decision should be made on the results from a single range session.
The largest single variable in the quest for accuracy is the capability of the shooter. Here the author tries out a very accurate Dakota Model 10 chambered for the equally accurate .220 Swift cartridge.
If the results from multiple range sessions determine that it is the rifle that has problems, the first and the simplest thing to check is the sights. These days that invariably means a scope and mounts. Make sure all screws are tight and nothing is moving. If they are, I'd even go so far as to swap scopes and mount one of known accuracy. I've had new scopes out of the box that wouldn't hold zero worth a whoop. If the sights are OK, then it's time to move on to the next step, checking the bedding of the metal to the stock.
BEDDING THE STOCK
There are basically three generally accepted methods of doing the bedding. Properly done, all seem to work well. These methods are full-pressure bedding of the action and barrel, fully free-floating the barrel with a pressure-bedded action and free-floating the barrel with upward pressure at the tip and a pressure-bedded action.
There is also a variation or two, such as pressure-bedding the action and the first three or four inches of the barrel and free-floating the remainder or pressure-bedding the action and the first three or four inches of the barrel, free-floating the rest of the barrel and then using upward pressure at the tip. Each method has its advocates and detractors. I believe the quality of the bedding is more important than the method that is used. By the way, these methods are the same whether the bedding is conventional or bedding pillars are used.
While the average shooter can do some checking to determine if the stock has warped and is bearing on the metal where it shouldn't, the correction of bedding problems is probably best left to a talented gunsmith. If, on the other hand, the shooter has a shop with the proper tools along with a modicum of wood-working skills, quite a bit of the work can be done at home.
If the stock doesn't appear to be binding on the metalwork, try torquing the screws that attach the stock to the metal with a consistent pressure. Curt Crum of the David Miller Company told me that he and Miller have found about 55 to 65 inch-pounds work best for them.
If your stock is synthetic you don't have to worry about warpage, you say. Think again, my friend. Synthetic stocks will move just as wood does. The only difference is the cause of the movement of the different materials. Wood warps and moves as a result of moisture. Synthetics, on the other hand, move as a result of temperature changes. In either case, check the bedding of a problem rifle, regardless of the type of stock on it.
Two very accurate hunting rifles from the shop of the David Miller Company in Tucson, Arizona. At top is a Miller Classic rifle, to my knowledge the most precisely built bolt-action rifle made today. It is also the most expensive that I am aware of. Also shown (above) from the Miller shop is the Marksman rifle. It doesn't have all the bells and whistles of the Classic, but it is about 40 percent as expensive. Both rifles are superbly accurate.
It is difficult if not impossible to shoot nice, tight groups with a factory trigger out of the box. A good example is a recent acquisition of mine, a Ruger M77 Mark II in 7x57 Mauser. I bought it from Brownells as a barreled action and had the company send it to Randy Boyd of Boyd's Gunstocks for one of his laminated stocks. Randy and his crew fitted one of their JRS classic stocks to my barreled action. The JRS stock was designed by my colleague and friend Jon R. Sundra.
The stock job was excellent, and the resulting rifle is really spiffy indeed. I could hardly wait to get it on the range. However, as it came from the factory, the trigger was stiff and heavy--I didn't measure it, but it must have had a minimum of a 10-pound trigg
er pull, possibly more. There is no way I could have shot tight groups with that rifle with its factory trigger.
I'm not picking on Ruger. Just about all factory rifles, regardless of the manufacturer, come from the factory with a "lawyer trigger." They are set at the factory to satisfy lawyers rather than shooters. These impossibly heavy triggers are a direct result of idiotic product-liability judgments against manufacturers in our court system. Anyway, with a quick trip to one of my favorite gunmsmiths the Ruger trigger problem was solved in short order. Several companies offer aftermarket triggers for the Ruger including Timney, Dayton Traister, Moyers and Spec-Tec. All are available from Brownells.
Ammunition is better today than it has ever been--no question about that. Factory ammo today is loaded with bullets that are more consistent, better constructed for hunting and more accurate than in the past. Cases are stronger and more uniform, and primers are cleaner burning and more consistent than ever. Many powders of different burning rates are available, and given enough time, the right one can be found to match a given rifle and cartridge. The machinery used in making the components and in loading the ammunition with those components is better and more precise than ever.
Thirty or 40 years ago the cause of most of the complaints about various cartridges was almost always a result of the ammunition (usually bullet failure) and not the cartridge itself. If Elmer Keith had used today's ammo instead of the stuff available during his time, he might have found something smaller than a .33 caliber with a 250-grain bullet adequate for most hunting. He might have even found the .270 Winchester to be an acceptable cartridge.
Factory ammunition is so good today that many hunters who previously handloaded all their ammo no longer do so. They have found that factory fodder is just as accurate as their reloads, perhaps even more so, and that they cannot duplicate factory velocities at safe pressure levels. They are perfectly happy with factory ammo.
Still, to extract every ounce of accuracy that a rifle is capable of, very precise and careful reloading is usually necessary. The key is, of course, consistency. Perhaps discussing how one expert goes about it would be useful.
In addition to producing arguably the finest bolt-action rifle ever made, David Miller is a fanatical hunter. He is also an expert long-range marksman. While some would call it extreme, the way he loads his ammo is a key component to his search for the most accurate tool he can come up with. He starts by running his bullets and brass through an Internal Concentricity Comparator (ICC) from Vern Juenke of The Accuracy Den in Reno, Nevada (775/345-0225). This machine compares each bullet (or case) and registers any variations on a scale readout. Brass and bullets that vary substantially from the others are set aside and either used for something less critical or discarded. The remaining cases are marked and kept together for their useful lives. The bullets are also segregated and remain together until they are shot.
Miller uses nothing but the most precise competition reloading equipment he can buy. He recuts primer pockets and precisely drills all the primer holes to ensure that all are uniform in diameter and depth. The cases are all weighed as well to ensure consistency. Once the cases are prepared, the primers are all uniformly seated to the exact same depth. Each charge is weighed, not measured, again for consistency. Finally, Miller applies molycoating to all his bullets before loading them into the meticulously prepared cases.
Proponents of molycoating cite numerous reasons for the process and sing loud praises for its attributes. Miller believes that the neck tension of the case upon the bullet and the release of the bullet from the case neck is much more consistent when using coated bullets. That makes pretty good sense to me.
You've done all that, and your rifle still won't shoot. Things are getting serious now and much more difficult to correct. If the action was not "blueprinted" in the early stages of building the rifle, it is almost like starting over to attempt it at this stage. The term "blueprinting" merely means that all surfaces are trued and are concentric with the bore. Most gunsmiths true on the barrel threads, and that usually works well. However, David Miller goes one step further. He and his colleague, Curt Crum, true on the raceway, remove the factory threads and cut new ones to ensure concentricity. They surface-grind the action with the exception of the front surface of the recoil lug and the front of the action ring. These two items are trued on a machine lathe after the barrel threads are recut.
Next to the capability of the shooter, the most important factor in accuracy is the barrel. Never skimp on the quality of a barrel if precise accuracy is a requirement. That is easily said, but how does one determine a quality barrel from an ordinary one? Alas, I know of no magic formula that guarantees barrel quality. While not foolproof, price and reputation of the maker are generally the best indicators of quality. Even so, the best of the makers turn out a lousy barrel every now and then.
Unfortunately, it is difficult if not impossible to determine if a barrel is a lemon until it's fitted to a rifle and taken to the range for a session or two. At that point, fixing a barrel problem is time-consuming and expensive. Not only is replacing the barrel required, but the replacement must be of precisely the same contour and size as the bad one or significant stockwork is also required. However, a rifle with a bad barrel cannot be made to shoot accurately no matter what one does. Replacement is really the only acceptable option.
Unfortunately, unless one is exceptionally talented and experienced, most of the corrective measures I have mentioned are best left to a professional gunsmith. Sometimes, for unknown reasons, the problem cannot be identified and therefore cannot be corrected. The best example of this that I know of is a rifle that I once owned. It was a petite little Husqvarna .270 with a full-length, Mannlicher-type stock. The first shot from a cold barrel would always shoot about 12 inches lower than the second and succeeding shots. After that first shot the remaining shots would group very tightly.
I took the rifle to several talented gunsmiths, but none succeeded in correcting the problem. That left me with the option of zeroing the rifle for the first shot and then holding a foot low on any succeeding shots or zeroing for the group and holding a foot high for the first shot. I chose a much wiser option and sold the rifle. I was totally honest with the buyer and told him up front of the problem. He was unconcerned as he was sure the problem was in the bedding, and he intended to have the rifle custom stocked. He did so, and last I heard the rifle was still doing the same thing. As far as I know he never figured out what the problem was either.
The accuracy of rifles available today has never been better. Many factory rifles out of the box will deliver consistent MOA-or-better groups. The quality of factory ammo has been improved to the point that much of it is better than most handloads. Still, accuracy is an elusive quality that many shoo
ters consistently try to better. There are many things that can and should be done in search of accuracy. If we progress in the next 30 years as much as we have in the past three decades, one-hole groups will not be unusual.
The one variable that is most difficult to control and conquer is the shooter himself. That may continue to be the one uncontrollable factor in our search for accuracy.