Ballistics question

[a9mmfan]

I was helping an aspiring writer do some firearms research and have a curious question myself. After a few internet searches it appears that the 308 caliber and sniper rifle are synonamous. Most either point to the 308 or skip up to the 50BMG. There seems to be some "middle ground" missing. Can anyone tell me why the 308 would be ballistacally superior to several others, such as 300 Win Mag, 3006, or 7 MM Magnum, for a 700-1000 yd range?

 

[Archie]

Sniper rifles.

There are two kinds of "snipers". Military and police.

Police sniper work is a precise strike at a single target. It is a response to a problem in place. Military sniper work is to harrass and discomfit the enemy. To make it difficult or impossible to continue his mission.

The .308 Winchester cartridge is the commonest U. S. sniper rifle cartridge. It is a very common hunting round for the same reason. It disposes adequate power without extreme recoil. The U. S. military already has the round in the supply chain, so there is no further complication. The round is also very popular in the civilian market, so a police department can readily obtain ammunition without special problems.

The .308 W is not ballistically superior to the other rounds you mention. All have been used one place or other as a sniper caliber. All, with the possible exception of the 7mm Rem, have more recoil (in similar rifles). The .308 W is simply the best compromise.

In police work, there are very few sniper actions that present targets at ranges exceeding 100 yards. Military snipers do, at times.

Does that answer your question?

 

[mark mcj]

While not a firearms expert or a sniper, I'll venture to say that the .308 is capable out to 1000+ yards on soft targets. There are better rounds to reach out further, but the ammo is not really very plentiful in a "combat" enviroment. Where the .308, is, a 7.62x51. A standard Nato round.

 

[Zak Smith]

[ sorry for the double-tap; I can't seem to delete only one of them ]

Unless you need devastating terminal ballistics at long, long range, as you would with something in an anti-material application, accuracy (that is, consistency) is more important than bullet drop.

In other words, if you already have ballistic tables for how your bullet will drop at the current range, and your scope has elevation knobs, you need only dial in the elevation and then shoot (ok, that's simplified, but you get the idea). Then the bullet must end up where you predicted it would, and that requires the entire rifle system be very consistent shot-to-shot.

The .308 is probably the most common choice today because the .308 replaced the .30-06 as the military round, and therefor it has been the focus of the most development, and the round itself is very well characterized.

That is not to say that it's impossible to build a very accurate "sniper" rifle in another caliber, just that it's easier to build an accurate rifle in a platform that has been the focus of accuracy development work chambered for a cartridge that's been well-studied for the last 30-40 years.

regards
Zak

 

[a9mmfan]

Thanks Guys, Great information!

 

[Jim K]

FWIW, the standard scoped rifle for the FBI Hostage Rescue Team is/was the Browning Automatic Rifle (the sporter, not the old military light machinegun) in .300 Winchester Magnum. They wanted something with longer range and more penetration than the .308/7.62 NATO. Where range and penetration are not necessary, the 5.56mm is in general police use, sometimes from a bolt action, but usually from an accurate AR-15/M16 type rifle.

Frequently, police snipers, especially on small departments, have used their own rifles, so there would be no general rule in that case.

An advantage of the military calibers is that special ammunition is available for special situations. Armor piercing, tracer, and incendiary are made for the 7.62 NATO, and the first two are made for the 5.56. (I don't know of an incendiary round for the 5.56, but the AP is the M995.)

Jim