By ‘compromise’ are you suggesting it’s accuracy is less? I find it pretty impossible to believe that a rifle less accurate at short range can be more accurate at long range. There are other ways I can imagine it being a problem, such as a snoper rifle being a lousy close quarters weapon because of its weight, barrel length and slow rate of fire, but accuracy?
Can someone with more knowledge than me comment on this?
Yes.
Here are some typical numbers:
.308
Bullet weight = 175 gr Ballistic coefficient = 0.496 Muzzle velocity = 2600 fps
At 100 yds: Time of flight = 0.12 sec Velocity = 2433 fps Remaining energy = 2301 ft-lb
At 1200 yds: Time of flight = 2.20 sec Velocity = 1107 fps Remaining energy = 476 ft-lb
.50
Bullet weight = 750 gr Ballistic coefficient = 0.994 Muzzle velocity = 2905 fps
At 100 yds: Time of flight = 0.11 sec Velocity = 2815 fps Remaining energy = 13196 ft-lb
At 1200 yds: Time of flight = 1.52 sec Velocity = 1929 fps Remaining energy = 6198 ft-lb
The .308 takes 44% longer to reach the 1200-yd target, so wind effects are substantially greater. And note that it retains only 20% of its 100-yd energy, vs 47% for the .50 bullet.
Also note that the .308’s velocity at 1200 yds is subsonic - the transition from supersonic to subsonic introduces additional inaccuracies.
Do bullets go to sleep?
Some people say they do.
This is counter-intuitive, I know. Nonetheless it has been well documented to occur by many and diverse shooters. The main thing to remember is that there are more factors at work than just distance to the target and bullet velocity.
Its accuracy at 100 yds will not be as good as that of a rifle optimized for that range.
Clearly this is not the same as saying that it will shoot a smaller group at 500 yds than it will at 100.
Not so clear if one is posting while drinking. I understand what you’re saying now. Thanks for the links as well, Scumpup.
Another factor (albeit one easily adjusted) that affects accuracy at various ranges is the droppage due to gravity. All bullets follow a trajectory which curves downward, so the further away your target is, the lower the bullet will hit relative to your aim point. You compensate for this by aiming your sights a little bit lower than the barrel is actually pointing. But since the bullet path is curved, but the line of sight is straight, you can only match exactly at one specific range at a time. A gun intended for sniping will be sighted in for a much longer range than one intended for use in general combat.
Yep.
A .given 50 BMG rifle will have less inherent accuracy at 100 yards than at 300 yards. In other words, if you were to mount the rifle in a vice, and shoot it at targets located at 100 yards and 300 yards, the groups at 100 yards will be slightly larger than the groups at 300 yards.
There is a reason for this. As soon as the bullet exits the muzzle - i.e., when the distance between the muzzle and the airborne bullet is just a few millimeters - the gasses that are exiting the muzzle will be at a higher velocity than the bullet. These gas molecules will impinge onto the base of the bullet, causing it to yaw and precess. The bullet will become more and more stable as it gets further from the muzzle, and will “go to sleep” after a few hundred yards.
At least this is the theory proposed by many shooters. Some shooters think it’s bunk.
I am calling bunk that one as well. I don’t see how it is possible. Any imperfections in accuracy should be amplified almost randomly in longer ranges thanks to chaos theory. I can believe the .50 BMG is remarkably stable over its entire flight path over other rounds and also that most of the instability is introduced in the first 100 yards and then settles down but there shouldn’t be any rifle that is more accurate at 300 yards and beyond than 100. How would it know to correct itself to the intended target?
That isn’t the same thing as sighting bias where you fire slightly upwards to at the muzzle in order to hit a target hundreds of yards away. You can correct for that. The grouping is the same even if you are a little off target in that case. You can’t correct for random deviations.
I have never shot a .50 BMG though although I have most every other type of rifle imaginable. Physics is a strange thing sometimes. I would be more than happy to see how that could possibly work but it doesn’t sound credible.
I’m not a precision shooter who spends his weekends trying to put all the bullets through the same hole at ungodly distances. I just spectate and occasionally spot. A fair few of the guys who actually do this kind of shooting accept this idea of bullets going to sleep, and they obsess over their guns, loads, and ballistics data like the average Doper obsesses over whether Greedo or Han shot first. I’m pretty arrogant, but not quite enough to tell competitive shooters who are manifestly better than I am that they don’t know what they’re talking about…especially when they can show me reams of data.
FTR, that last post wasn’t a shot at Shagnasty. All I meant was that people who shoot a lot more and a lot better than I do are convinced that bullets do go to sleep.
This seems most unlikely. It’s reasonably easy to see how the angular size of the 300-yd group might be smaller, but not the absolute size.
You provide a plausible explanation for a reduction in the angular size of the shot group - but this doesn’t work as an explanation of a smaller absolute size. The bullets that are dispersed at 100 yds would need to undergo some sort of magic force that draws them back together at 300 yds.
Another problem with this theory is that if the group at 300 yds is smaller, it means the bullets are converging as they cover the distance from 100 to 300 yds. It follows that they are then dispersing after they pass 300 yds. At, say, 1000 yds the spread would be horrible - which is not what’s observed.
I’m sure that there are some obsessive gun nuts who do insist that. There are also obsessive audiophiles who insist that gold-plated cables are better, even though they can’t tell the difference in blind tests.
But that’s what I’ve been trying to get at…does that round from that weapon actually shoot farther than smaller projectile rounds from other rifled, sniper-styled weapons? And more accurately, too? I was led to believe by some of your earlier posts that this wasn’t the case due to heavier rounds, the weight of the weapon itself, etc…but there HAS to be a reason Special Forces and the like continue to favor it as a weapon of choice for the job of “taking someone/something out at seriously ridiculous ranges”.
quibble, actually 2. Bullet crosses the sight line on the way up and again on the way back down.
Good hunters (or snipers) are very aware of this and can compensate on the fly. For example, my dads .30-06 is sighted for 200m, if deer is at 100m aim a tiny bit low as the bullet will actually be above the sight line at that point.
Graphic on this page shows an example.
I have heard of rifles being aimed to cross at like 100m on the way up then back down at like 350m.
Here’s the thing, FGIE: the .50 BMG projectile has a ridiculously high ballistic coefficient. The 750 grain Hornady A-Max .510 in projectile has a BC (G1) of 1.050. (I know, the M2 Ball isn’t equivalent to the A-Max, but it’s close, isn’t it?) OTOH, A .308 in., 168 grain Sierra Boattail MatchKing projectile (which was, IIRC, what Vietnam era snipers shot) has a BC G1 of .462. Even if you rock out to the 240 grain boattail, (which would need to be seated hella deep in a .300 WinMag or greater), its BC is .711. Higher BC’s mean that the projectile suffers less drag and consequently keeps its velocity higher, longer. Frankly, I can’t see why Special Forces would be eager to carry a friggin 30 pound rifle with 1/4 pound ammo, up hill and down dale. If you’re GSGT Hathcock sitting on Nui Ba Den with an M2HB, that’s one thing. If you have to carry the thing throughout Afghanistan, that’s something else. I’m not seeing what the extra range is buying you, in an environment where you should have total air superiority.
All of this is kinda’ silly, anyways. The USMC has it right, IMHO, by calling these soldiers Scout/Snipers. The scouting is more important than the sniping. If they need to neutralize what they’re observing, with a radio, the Scout/Snipers can have some other element do the killing. A 500 lb JDAM kills anything that a .50 BMG round will, even a Raufoss. And incidentally, not give away their position.
I am interested in reading more about Scumpup’s comments about both sleeping bullets, and barely-stabilized bullets being more accurate. I’ve read a few cites that confirm his comments, but I’m having a difficult time seeing the theoretical reasons why.
The difference, of course, is that the shooter can show targets shot with different loads at varying distances. The holes in the paper are either a distance apart to support the claim or they are not. The measuring need not even be done by the shooter.
Just to get back to the original question, yes certain rifles are constructed for and designated as sniper rifles. An example is the Accuracy International L115A3 which was famously used by British Corporal Craig Harrison in Afghanistan. This highly specialised weapon cost the British Ministry of Defence GBP23,000 (US$34,000), weighs 6.8 kilograms, and fires an 8.59mm bullet. Its akin to an Olympic target rifle and indeed is derived from such.
And the enthusiastic puff you’ll find online and in magazines about heavy calibre sniper rifles is just that - puff. Wide eyed hotblooded enthusiasm for a mega weapon from people who have no conception of what 12.95mm (.50 cal) requires and is designed for.
The Barrett (hallowed be thy name :D) is an extraordinary machine, capable of semi-auto fire way over 1000m, with sustained accuracy. However as pointed out above, a 50 cal rifle is not for shooting enemy combatants. Oh yes you can do it, but then a .762 (308) does it easier and possibly faster. The Barrett is an anti-materiel weapon which makes complete holes in vehicle engines, light armour, buildings, you name it and hit it, some damage gets done.
However even a superman soldier would not want to haul a Barrett around for very long. Its a very hefty and long rifle with big ammo. It likes to be driven from point to point.
This should probably be “a 7.62 (.308) …”
The Barrett is also used by combat engineers for EOD work. Spot something that might be a IED or sundry explosive device, put a couple of .50" rounds in it from a safe distance, and if it doesn’t explode then, it probably never will.
