Ammo, Velocity, Barrel Length, Effective Range

[JediGuy]

With the exception of some specific target models, rifles are weapons designed to send a projectile into the body mass of a living creature, causing, by velocity and mass, enough damage to stop the creature from functioning, whether a human combatant or a game animal or a pest. Semi auto rifles with detachable box magazines such as the M4 are weapons designed specifically to maximize killing effectiveness for a foot soldier, with a round designed for humans (as opposed to game) and enough rounds to allow for repeated hits on one or multiple adversaries.

Starting from that proposition, what range are you comfortable using for M4/AR derivative weapon for its intended purpose with typical military or bulk full metal jacket ammunition?

I ask, because I read regularly how someone is going to take their 10.3 or 11.5 micro self defense carbine out to 150-300 yards, etc. Yet, a little math done a long time ago told me my 12.5” was generally good to between 75-100 yards depending on ammo selection. I don’t recall efficacy of most bulk ammo through a 16” barrel, but I don’t think it was 600 yards. This is not to say that a round from my 12.5” at 150 yards isn’t going to end a life or cause a really bad day. Rather... I’m asking whether that is the good, reasonable, or (to use game hunting terminology though the situation is not the same) ethical thing to expect of a chosen weapon.
Note: None of us want to use our carbines for their original purpose. I get that. But then people will bring up “SHTF” and similar, so it does seem like something that has value in discussion.

Considering most people* (*generalization without concrete evidence) don’t purchase true defensive ammo, instead using various FMJ .223 or 5.56 loads, with some Mk262 thrown in for good measure, are a majority of AR owners deluding themselves?

For those that use their AR derivatives for their original purpose, what do you find to be a reasonable expectation of your current carbine, specifically as relates to distance and ammo choice?

If nothing else, I hope this makes people consider their own expectations. Or someone can tell me I’m way off base.

[grizzlyblake]

My ARs are for defense or offense if needed from human adversaries. I settled on 16” barrels, Speer and Federal 62gr bonded SP, and Aimpoints for my expected use. I would guess that’s 200yd and in which keeps velocity above 1800fps for reliable expansion.

[grizzman]

My handload, using a 65 grain Sierra GameKing should have a muzzle velocity of 2565 from my 11.5" Sionics (using Ramshot TAC). I haven't chrono'd it yet, so I'll use what QuickLOAD shows.

Sierra Infinity shows that using 1800 fps as my velocity limit for expansion, the velocity drops below 1800 fps at 500 yards. It's got an MRO, so I will simply consider it's maximum effective range to be limited by my ability to deliver a solid impact on target, likely between 250 and 300 yards.

With the 16" with a 1-6 LPVO (and a solid shooting position) effectiveness to the 1800 fps point at 650 yards sounds very reasonable.

Those that use FMJ for anything besides training/bunching paper/ringing steel are....well, I was raised that if I can't say something nice....

[Pappabear]

I would think 500 yards but I've never killed anyone so......The iron sights on these guns go to 500, just a thought.

PB

[SBRSarge]

My 10.5 SBR throws Federal 62 gr loads between 2575 (LE223T3) and 2650 fps (XM556FBIT3). This should put the expansion distance out to 350 or 400 yards or so using 1350 as minimum expansion velocity.

The 62 Gr Barnes TSX at 2665 should be good to 275 or so yards or so using 1900 as M.E.V.

Winchester Ranger 64gr at 2600 should be good to 300 or so using M.E.V. of 1600

These are from memory without consulting a ballistics chart but should be pretty darn close as I was researching this not too long ago.


Edit to add: These velocities were measured with a SilencerCo Omega on the gun

[markm]

I only have one can of Mil Ball. All else is 75-77 gr. So 500 yards is highly doable with that bullet our of a 14.5" (I'd have to have binoculars to I.D. a bad guy, but I could let the air out of them with a dot or irons.)

[vicious_cb]

Take a look at the .308 vs 6.5C thread. As distance increases the importance of terminal ballistics becomes less and less and it becomes more about getting hits on target. The problem with shooting ball ammo at distance is its poor accuracy.

[yoni]

I have used a 10.5" barrelled rifle and a 11.5 ", a 14.5" and a 20".

I always tried to stay with guns that allowed me to use 55 grain rounds over the 63grain green tip because it worked better. Most real shooting unless your in the middle of a flat desert will be much closer than you think, 100 to 150 max, most of it will be 75 yards or less in urban settings.

[Sid Post]

...

Those that use FMJ for anything besides training/bunching paper/ringing steel are....well, I was raised that if I can't say something nice....

Real M193 pressure spec out of my KAC SR-15 LPR (18" barrel) on a 20~30lb dog worked exceptionally well. In a dead flat full out hard run towards me, the round entered the open mouth and absolutely stopped the front in place and the rear end came up and over. Seriously, it was like that dog hit an absolutely impenetrable wall.

The 55gr FMJ hand grenaded in the body with no fragments breaking the skin. I'd call that a win.

In terms of being effective at a range, it really depends on the target. Are they wearing a T-shirt or Leather jacket? Are they sober or bulletproof thanks to modern street drugs or booze?

If I'm shooting at ~200 yards, I have time to shoot again if I need too. Closer in, even M193 will work if you get reasonable shot placement. DRT works the same whether using bulk blaster ammo or an AFRICAN boomer! In fact, I dare say my M193 is more effective in an anti-personnel role than my 470NE or any of my big CZ 550's (9.3x62 through 458 Lott).

[grizzlyblake]

How about just buy ammo that is designed for shooting people instead of justifying cheap ball ammo? It's odd that this isn't a thing when it comes to pistols. People realize 9mm NATO ball sucks compared to any good JHP bullet.

Yeah, a thousand rounds of 62gr Bonded SP costs a little money, but this is a forum dedicated to duty ARs, not garagebuiltAK.net.