Is there something about a bolt action rifle that makes it actually more accurate?

So in all the video games…and, apparently, in real life…the bolt action rifle is the rifle that snipers use. Famed sniper Chris Kyle, who as a Seal had probably open access to the armory, used a Remington 700 as his “best” rifle.

What gives? Isn’t the accuracy of a firearm determined by the barrel length and quality, the quality and consistency of the ammunition, and alignment with the aimpoint at the instant of firing? None of these factors would be affected by the way the weapon cycles ammunition, and even a “perfect” sniper shot is affected by wind and slight variances in the bullet. This means that at long ranges, the circular error probable is bigger than the target profile, and misses are inevitable - but the more shots a sniper fires, the higher the overall chance at least one shot hits.

Anyways, why are the best sniper rifles bolt action?

You’re going to get all kinds of answers to this but they all then to boil down to the fact that the Remington 700 is simply a very good rifle. The mechanically simple, manual cycling of a bolt action provides a very firm lockup of the shell in the chamber. Semi and full auto weapons have more complicated designs and tend to have greater clearances and looser fits in order to provide for fast cycling. A ‘feature’ that is either meaningless or detrimental for a sniper.

Please bear in mind that I’m not saying you can’t find highly accurate, semi-auto rifles. They’re out there. They also tend to be more expensive and less tolerant of neglect than the simple, proven Remington.

There is exactly one reason for this, and it’s that the glare and sound of ejected casings give away away the shooter’s position. Bolt action rifles let the shooter control those events.

The action very much affects the accuracy of the rifle. With a semi-automatic rifle some of the gas is diverted which could be used to propel the projectile, and while the action is delayed it still opens early enough to potentially affect the shot. With a bolt-action rifle all of the gas goes to the shot and the breech remains locked until the operator unlocks it.

Walther made a semi-automatic sniper rifle, the WA2000, and it wasn’t successful. Anecdotally it wasn’t quite as accurate (though the average shooter wouldn’t notice), it was ludicrously expensive, and it wasn’t durable enough to be an effective deployed weapon. Bolt actions are simplicity itself in comparison.

They’re not. At least not anymore. Rifles such as the SR-25/Mark 11 Mod 0, M110 SASS, and the sniper version of the FN SCAR, among others, are easily accurate enough to fulfill the requirements of the sniper mission, and are used by members of groups like the US Special Operations Command in the sniper role. Moreover, and probably more importantly, they provide an increase in aimed rate of fire over their bolt action counterparts, British WW1 Lee-Enfield anecdotes aside.

My guess is that a bolt action is mechanically easier than a semi auto to make true, concentric, and have more consistent lockup. I would have said that it’s also easier to make a consistent bolt action for powerful cartridges like .338 Lapua Magnum, but plenty of companies make accurate semi-auto actions for .50 BMG.

Airman Doors brings up an interesting point. Gas is used in some semi-automatic actions to cycle the action, gas pressure that isn’t available for propelling the bullet. What sort of velocity loss can be expected as a result of that? I honestly don’t know.

Aside, there has been some research done to demonstrate that shorter barrels can be more accurate than longer ones—they’re stiffer, for one. They may show velocity losses relative to longer barrels, and if using iron sights, a longer barrel can provide for a longer sight radius.

I thought rate-of-fire (ROF) is the last thing a sniper is concerned with. If you are firing rapidly the second shot just cannot be as accurate as the first shot. When at close(ish) ranges that may not be a big deal but if you are a sniper chances are you are taking very long range shots. Do they really want more than a shot per trigger pull (or semi-auto…a shot per trigger pull as fast as they can manage)? Seems to go against the notion of what a sniper does.

When I joined the Israeli army in 1993, the standard-issue sniper rifle was the semi-automatic M-21, a modification of the M-14. At some point during the early 2000s, they were all replaced with bolt-action M-24s. I doubt it was a matter of budget - M-14s are still easy to find and mod. For whatever reason, the IDF , which generally prefers versatility over overspecialization, still decided to go with bolt-action over semi-auto.

I am just guessing here but seems the psychology of it could matter.

A sniper is meant to take a very considered, very well aimed shot. Anything that shoots faster than a bolt-action is not in line with that goal. And if you give someone something that fires faster they may be inclined to try and pop off a second and third shot in rapid succession if they miss the first. All things that are not in keeping with what you want a sniper to do.

So, remove temptation – give them a super accurate but also cheap (relatively speaking) weapon and you get better results. Win - win.

That makes sense.

A bit of research shows that sniping and sharpshooting have undergone a major revolution since my regular service days. Back then, there was one sniper per platoon, whose job was to provide accurate suppression fire. With the introduction of assault rifle-mounted scopes in the late nineties, multiple squad-level “designated marksmen” replaced the platoon sniper, and actual sniping was pushed up to the battalion level, with snipers given M-24s, much more training, and a more specialized role.

WAG: You don’t want to carry two rifles. Sniping is a combat role, meaning that you’re liable to be in the combat zone, meaning that you’re more likely to see close combat than you’d really like to see while carrying a bolt-action rifle. Ergo, you want a multi-purpose weapon; one which can be used both as a sniper rifle and as a regular soldier’s rifle.

Airman Doors USAF nailed it earlier. It’s about the action, or more precisely the lack thereof (and the lack of cyclic motion of the action), and the directing of the spent gasses. Every moving part in the action introduces some variability in their movement.

That’s what I’ve always heard. You don’t want the weapon doing other shit while your projectile is being sent on its carefully-planned trajectory. You want to deliver the projectile as perfectly as possible into the hands of the ballistic gods and THEN do whatever you want to do next, like cycle another round or bug out.

But doesn’t the sound of a bolt action rifle loading and u loading also give away positions? Also is that level of sound at several hundred meters really noticeable?

Not at that range, and if you slide the bolt carefully it doesn’t make that much noise.

At one point, US Special Forces and some other units were using modified M-14s for snipers.

What makes the bolt action rifle accurate is that the breech, chamber and barrel are one piece. As a result, there’s no deviation due to pieces fitted together and flex.

The aforementioned M21.

I don’t know if that’s the one and only reason, but it is one that’s not subject to debate whether it really exists.

For the accuracy related ones it is pretty clearly is debatable, just since various armed forces have gone back and forth between using gas operated autoloaders and bolt action rifles as sniper weapons. The stuff mentioned like some theoretically greater variability in velocity because of inconsistent gas take off (it wouldn’t be the fact that some gas is diverted if it was 100% the same every time), or greater tolerances to facilitate easy movement of the action, those could be true. Another one only obliquely referred to previously is vibration and bending in a longer barrel due to cycling of an autoloading action that could potentially start before the bullet is out of the barrel. There’s some reaction of the barrel to the gas piston pushing back on the action.

But, are they really significant enough to care about? That also depends as was alluded to what exact role the ‘sniper’ is playing: ‘sharp shooter’, ‘designated marksman’ v a ‘true sniper’. And for example police snipers are typically firing at short ranges where a very good shot in reasonable conditions can really put bullets in a particular part of a human size target perhaps with low enough risk to an innocent hostage standing right nearby. In long range military situations that’s not necessarily possible, no matter what’s shown in movies or told as legends of great snipers. It’s some probability of hitting a human size target and following up misses with further shots without losing the sighting picture, as you can more easily do with an autoloader, might be advantageous.

Yes, but think- all line infantry have been armed with autoloaders since the 1950’s or so, there must be something good about bolt actions for sniping that the military often still uses them in this day & age.

But with an autoloader you can’t put ear wax on each round too easily.