What Makes an Accurate Barrel?
February 14, 2011
Rifle accuracy depends first and foremost on the barrel.
The inside of a rifle bore.
Rifle accuracy depends first and foremost on the barrel. Everything else matters: sound bedding, concentric action-to-barrel mating, consistent ammo, well-cut chamber and crown, and good bullets. But if the barrel isn't straight and cut with true and clean rifling, none of these matter.
Problem is, very few among us--myself included--can tell a good barrel just by looking at it. Come to think of it, a barrel has to be pretty darned bad before you can look at it and know for sure.
Yes, you can tell if a barrel is pitted from neglect, and you can tell if the throat is washed, and in extreme cases you can tell if the rifling is worn.
A bore scope will tell you quite a lot more, with many new barrels showing tool marks and rifling that seems almost jagged. But here's the rub (so to speak): While indicators such as these aren't desirable, none of them offer surefire proof that the dog won't hunt.
Some barrels that show significant wear, have pitted bores or rough rifling shoot extremely well. And some barrels that look perfect steadfastly refuse to group, no matter what you do.
This is part of the frustrating fun of messing with rifles. You really don't know what you have going until you sit down at the bench. Even then you may not know until you've tried a bunch of loads, checked the bedding, switched scopes, perhaps recut the crown, and tried a half-dozen other tricks before you finally sigh with satisfaction--or walk away in disgust.
If you're embarking on a custom rifle project, whether fancy or plain, the best advice I can give you is to start with a really good barrel. There are lots of good ones from many makers, and most makers grade their barrels.
The difference between a $100 replacement barrel and a selected match-grade barrel costing several times more may not be discernible to the casual eye, but there is a difference. With luck, an average barrel can deliver exceptional accuracy, but with sound assembly and good ammo a top-quality barrel will deliver truly exceptional accuracy.
With factory rifles you don't have the luxury of selecting your barrel. There will be some range of accuracy--with most customers satisfied, some pleasantly surprised and a few frustrated.
But, realistically, factory barrels are darned good. If you figure what the manufacturer of a rifle retailing for $500 has invested in just the barrel of that rifle--nothing close to $50--over-the-counter accuracy is truly amazing today.
I would never suggest that the best hand-selected, match-grade custom barrel costing $500 will shoot 10 times better than a $50 factory barrel. On the other hand, accuracy gains are generally incremental, almost never exponential--and, man, are we spoiled these days.
We take it almost for granted that a factory rifle will produce minute-of-angle accuracy, and we're bummed when they don't. A large percentage will, at least some of the time with some loads. A very few will cut that in half, which is truly spectacular for a production barrel. But to cut that in half again, down to a quarter-inch group, is a huge leap--and to obtain that level of accuracy on a consistent basis is yet another leap.
Believe it or not, caliber can also make a difference--not in theory but certainly in practice. I remember when Geoff Miller and I were contemplating a long-barreled 8mm Remington Magnum as the "ultimate long-range elk rifle." Kenny Jarrett, another guy who knows much more about rifle accuracy than I will ever learn, advised against it because he figured we'd have a hard time getting a really good 8mm barrel.
Perhaps we got lucky. Norm Bridge, a great old riflesmith, put the rifle together. He commented that the Pac-Nor barrel we used was one of the best barrels he'd ever seen. The result was truly exceptional accuracy, but I tend to think Kenny was exactly right: The odds of getting really exceptional barrels are probably better with the most popular bore diameters.
What got me thinking about this was correspondence with a friend of mine, Andy Drook, who just purchased a .264 Winchester Magnum. Historically, the 6.5mm hasn't been very popular in the U.S., so why should the factories put extra effort into their 6.5mm barrels?When the .260 Remington came out in the late 1990s, there was much hype about its exceptional inherent accuracy. However, I went through three production .260s, and I was not impressed.
They were "okay," but no more accurate than similar 7mm-08s and seemingly a lot more finicky. The problem could well have been an exceptional cartridge trapped in average barrels--and further hindered by a limited selection of bullets.
This is changing, at least in the case of the 6.5mm. A few years ago, another rifle-nut-friend, Marv Quillen, got hold of a couple of really good Obermeyer 6.5mm barrels. I latched onto one, and the ultimate result in .264 Winchester Magnum is at least as accurate as that cartridge should ever be expected to be.
Today it wouldn't be foolish at all to choose a 6.5mm if you were looking for a tackdriver.
Thanks to the current popularity of exceptionally accurate 6.5s such as the 6.5-.284 and 6.5 Creedmoor in long-range competitive shooting, things are a bit different today. You can definitely get really good 6.5mm barrels from any "name" barrel maker, and there are plenty of bullets developed for accuracy.
So today it wouldn't be foolish at all to choose a 6.5mm if you were looking for a tackdriver. And of course that applies to any of the other popular bore diameters.
But if you're one of those riflemen who feels compelled to do something different--like my 8mm, or maybe a .311, or like my old friend Charlie Askins, who wildcatted a .290 "just because there wasn't one"--if accuracy is your goal you'd better count on some luck.