wounding characteristics of subsonic rifle rounds

[TheDan]

We've covered wounding characteristics of handgun rounds and rifle rounds here ad-nauseum, but one thing I've been wondering about is subsonic rifle rounds. Pistol rounds mainly just cause crushing damage due to their low velocity. Rifle round's high velocity make them do all sorts of fun things in the body. So if a rifle bullet is lowered to below the speed of sound (~1125fps), does it only cause crushing damage like a pistol round? If so, whats the advantage of a subsonic rifle round? If you were wanting to only shoot subsonic rounds, wouldn't it be better to just stick to wide and slow bullet from the factory like .45acp?

 

[Mikewood]

Exactly. A rifle bullet at low velocities is really just a small pistol bullet and a FMJ at that. It might tumble upon impact but you can't count on it. If you want to do maximum damage below the speed of sound you need diameter. But all things being the same a can with a larger diameter is louder. If all you have to shoot is a rifle and you want to be really quiet you shoot subsonic knowing it does not work well.

 

[M. Sage]

Yes, a subsonic rifle round is just going to produce crushing damage. Most anything under about 2000 feet per second is going to be restricted to crushing damage only (the M1 Carbine does handgun-like damage, for example).

Smaller diameter bullets can give you better external ballistics, though. .45 ACP's fat slugs aren't exactly good for lobbing out 200 yards. Something in a similar weight class but around .30 cal is going to retain a lot more velocity and get pushed around by the wind a lot less.