Apologies if this has been asked & answered, but a search didn’t show anything appropriate.
Why are sniper rifles allways bolt action? Presumably they are more accurate but why would that be the case?
Thanks for your help
Well, in more recent times, there has been at least one
very fine sniper rifle that’s semi-auto instead of
hand-actuated bolt. I’m referring of course to the
Heckler & Koch PSG-1. Nice pics here:
http://www.hkpro.com/psg1.htm, also a blurb at the
bottom of this page: http://www.streetpro.com/usp/hkrifle.html
As a WAG, I’d guess that the action of the bolt
coming back might throw off the aim a little bit.
This is no big deal on a handgun, but on a
sniper rifle where a fraction of a degree can
literally mean the difference between life and death,
it’s rather more important.
It’s interesting to note that several PSG-1 pages
mention the special “fire from closed bolt/delayed
blowback” mechanism of the PSG-1.
-Ben
Well, you can have a
- Single shot rifle
- Lever action rifle
- Bolt Action rifle
- Semi-automatic rifle
- Fully automatic rifle
(Am I missing any?)
No. 5 is notoriously inaccurate, which needs no explaining. No. 4, while much more accurate than no. 5, still has parts that are moving immediately after firing the cartridge. (Anything moving immediately before or after the time of firing is going to decrease accuracy.) No. 2 is a somewhat outdated design, and not nearly as reliable as no. 3. Theoretically, and all else being equal, no. 1 should be most accurate, but it certainly isn’t convenient.
That leaves us with no. 3: bolt action. A bolt action gun is the best all-around performer when it comes to reliability, accuracy, and convenience.
OK that makes sense. I didn’t think of the movement of the mechanisms before the bullet has left the barrel. I guess that would throw the aim off enough.
Wonder how well that HK gets around it.
Barrett makes a very fine single-shot rifle, quite effective for sniping. Please note that even single-shot rifles need some method of placing the round in the chamber. That said, your commentary is fairly accurate. Two of the bigger issues in rifle accuracy, from an action point-of-view, are tolerances and action strength. Bolt-action rifles tend to be very strong, and can be manufactured to very tight tolerances. Lever-action rifles tend to have fairly loose tollerances, as do most semi-auto rifles. This doesn’t mean that they can’t be made as accurate as bolt action rifles, but makes the task more difficult. Harder to do == More cost == Fewer rifles :. The military goes for the bolt-action rifles. One notable exception to the ‘bolt-action-only’ trend was the XM-21, a Ft. Benning accurized M-14 semi-auto rifle. This is the rifle that GySgt. Carlos Hathcock used in VietNam to such great effect.
FWIW the US has almost exclusively used bolt action rifles in the last hundred years. Exceptions were the M1D and a variant of the M-14. The M40 rifle series in use for the last thirty years or so is at it’s heart a Remington model 700 in 7.62mm (.308 Winchester), one of the most common types of hunting rifles.
The solid construction of a bolt action rifle lends itself to more accurate bedding in the stock. With the M40 the reciever is solidly bedded while the barrel floats free, not touching anything. Semi-auto rifles can be designed that way but few are. Bolt action rifles are less prone to malfunctions because the shooter can operate the bolt with as much pressure as is required for extracting or loading. All in all bolt action rifles are very mature technolgy, more robust and less finicky than most self loaders.
The NRA magazine just ran an article on the development of the M40 if you’re still curious.
Crafter, don’t give the mistaken impression that a single shot is somehow less reliable. There are competetive shooters using 125 year old designs like the Sharps, Remington rolling block and even the trapdoor springfield that could give modern rifles a run for their money.
villa, bolt movement isn’t as big a problem as you’d think. Ideally nothing would move until the bullet leaves the barrel but consistent movement that doesn’t happen too soon isn’t a big problem in the real world. I’ve got an AR-15 type that has a few accuracy modifications that is capable of sub-MOA grops.
For those not familiar with the term MOA means minute of angle, 1/60 of a degree. This is shorthand for a string of shots at 100 yards that all impact in a 1" circle.
That should read: This is one of the rifles that GySgt. Carlos Hathcock used in VietNam to such great effect.
Sorry about that.
I got to say, why I didn’t think of using the SD for novel research before defeats me!
So, realistically, what sort of rate of fire could you expect from a qualified sniper with a bolt action weapon?
villa, a good bolt gun shooter is capable of astonishing speed but it’s a mostly a moot point because guns like the M40 only hold 5 rounds IIRC. The craft of a sniper (or varminter for folks whose hobby is not shooting people) is finding the perfect position time to make a single shot do the job.
Military snipers are paired with a spotter/support person who is armed with a self loader like an M14. That puppy holds 20 rounds in a standard magazine so rate of fire is a more relavent thing.
FWIW bolt action rifles can be fitted with high capacity M-14 magazines but the military never does this. The M40’s fixed box magazine is permanently welded to the reciever to make a single solid unit.
Nobody has mentioned yet the fact that semi-auto rifles generate less power than bolt actions. Some of the gas necessary for bullet propulsion has to be diverted away from the bullet to operate the blowback mechanism, leading to a loss of power. Not exactly conducive to long range accuracy.
For an idea of range of sniper fire, the British army trials for the 7.62 PKM sniper rifle required a first round hit at 600m and accurate harassing fire out to 1km, which the rifle achieved with ease. Apparently harassing fire out to 2km can be achieved, but bullet energy is so low at that range that damage is minimal.
As for speed of fire, in 1914 a British Sargeant using a bolt action, open sighted Lee-Enfield fired 38 shots in one minute, putting every one into the inner ring of a target at 300 yards (272m), which is still the worlds record. Bearing in mind the Lee-Enfield uses a 10-round magazine this gives a fair idea of what sort of rate of fire a sniper is capable of. Telescopic sites would probably reduce this rate of fire, as would trying for definite kills (head shots basically). And of course very rarely will the enemy be standing still, in the open waiting for a sniper to pick off 38 of them.
Gaspode, any velocity lost from the gas diverted is negligible if measurable at all. Gas ports are a fraction of the bore size and close to the muzzle. Most semi autos have relatively short barrels and that’s where the difference comes from.
That’s pretty impressive shooting, especially given the fact that I never managed to put 10 rounds into a .303 without jamming it.
It does help, though to show what one person might be capable of - but I guess the ideal is one sniper, one target.
villa wrote
Actually it is one sniper, one spotter (as Padeye mentioned) and one target.
In the US the spotter is utilized not so much for his spotting abilities but for a less obvious reason. He shares the responsibility for the kill with the actual sniper. The US military found that two people sharing the feeling of guilt for killing another human, would help eliminate any hesitation a single shooter might have.
BTW- this info was related to me by a drunken Ranger Sniper, but has been supported by several sober military men as well.
I remember in the UK hearing that only half the rifles for a firing squad are loaded with live ammo for the same reason. Do you know if that is true for the US military?
villa asked-
Honestly, I do not know. But it does sound familiar and makes good sense.
I do know though, that some states that impose the death penalty via the electric chair use multiple switches with only one being operable. Three people pull the levers and none are sure if they did the deed.
BTW- I, being the vengeful bastard that I am, would have absolutely no problem pulling the lever on some of these characters. I could even wear a T-shirt saying I did it.
It’s been a d*mned long time since anyone was executed by firing squad in the US military, but, AIR, the NCO in charge of the detail loads the rifles (5 is traditional), and one of the rifles is loaded with a blank round. Obviously, with self-extracting rifles, the element of doubt is greatly reduced, thus, bolt-action rifles are recommended. The shooters aren’t supposed to operate the actions on their weapons afterwards, again, to preserve doubt.
IIRC I read that one of the rifles used in Gary Gilmore’s execution in Utah was loaded with a blank. Memory is a bit fuzzy but they may have actually obscured the condemned with a curtain that had an aiming spot over his heart.
I think those methods of removing guilt work better on paper than IRL.
FWIW rifles like the FAL/L1A1 have a gas port valve that can be turned off. This is for launching rifle grenadeds but effectively turns the rifle into a manually operated one as the spent round will not eject on its own. It also greatly increases recoil. I’m not aware of any rifle in the US inventory that has this feature as we use a different type of propelled grenade.
Shuting off the gas port will make your shoulder hurt. It’s also very hard on the rifle, and reduces it’s useful life. The US gave up rifle-grenades when the M-79 and M-203 came along. These (and their descendents) fire 40mm grenages further, more accurately, and to greater effect than the rifle-grenade.