Question for the AR guru's

[bobzilla]

What is the max range of a 16" bbl AR? Consistent that is? would a 20" bring better accuracy downrange farther?

Considering doing a build and looking into what would be best for an all purpose gun.

 

[sloughfoot]

Look up USMC. They use the 20 inch as their all purpose rifle.

 

[Hop]

Bullet drop out past 200 yards starts to get severe. It's down ~20" from peak at 400. 400-600 is probably the limit for a 16" barrel.

Check the zero charts on M4C: AR-15 Zeros and Trajectories - M4Carbine.net Forums

 

[neraph]

I think it ultimately depends upon what purposes you include in "all purpose".

Is this a SHTF / paper punching / coyote-hunting gun?
If that's the case, then which SHTF situation are you preparing for?

Anyways, a few things about ballistics:

Generally speaking, a shorter barrel will be more accurate for a given barrel profile. There are, of course, many variables that affect the accuracy of a gun, barrel length is just one of them. The extended supersonic range that you get with a longer barrel may outweigh this if you're looking to shoot out at 600-800yds, depending on the ballistic coefficient of the bullets you intend to use.

One of the reasons the USMC uses 20" barrels is because they get better terminal ballistics than the M4 carbines. If you're not limited to FMJ bullets, this really isn't a concern. Of course, this is not the only benefit.

If you're trying to maximise the point blank range of the gun, then the greater muzzle velocities will definitely aid that, but knowing the proper zero range will make a much greater difference as will proper bullet selection.

-----

The short answer is, bullet selection will make a far greater difference than a 16" or 20" barrel will. Having a higher quality barrel will make a much greater difference in accuracy than barrel length. Your ability to stabilise and aim the rifle will make a much greater difference in accuracy than barrel length.

 

[shibumiseeker]

Further than you can shoot accurately

400-600 yards give or take.

A 20" bbl will buy you a little more velocity which will in turn give you a little more range, but the tradeoff is needing a stiffer barrel to get the same inherent accuracy. The difference between the 16 and the 20 using the same ammunition is maybe a hundred yards give or take at the same level of accuracy.

Note: That's not the maximum range, that's the accuracy range.

 

[Fordtough25]

Further than you can shoot accurately

400-600 yards give or take.

A 20" bbl will buy you a little more velocity which will in turn give you a little more range, but the tradeoff is needing a stiffer barrel to get the same inherent accuracy. The difference between the 16 and the 20 using the same ammunition is maybe a hundred yards give or take at the same level of accuracy.

Note: That's not the maximum range, that's the accuracy range.

This.

 

[bobzilla]

16" IT IS! That's what I was curious about. If I want to reach out past 300yds I'll find a better tool!

 

[LPMan59]

i say get one of each

 

[bobzilla]

I still want one of those SA M1A's as well. I'm going to need a bigger paycheck.

 

[cgbills]

if you like 308 you could do a AR10 type build. DPMS 308s can be had for the same price as 5.56

 

[melensdad]

Maximum accurate range is based, among other things, on keeping the bullet supersonic. Longer barrels generally yield higher velocities. But bullet choices are critical too, the higher the ballistic coefficient the more wind defying the bullet will be, that aids in keeping the bullet flying at supersonic speeds longer.

A heavy barrel 24 inch barrel combined with a sleek bullet will be theoretically accurate to a farther distance than a 20 inch barrel with the same bullet and that will be accurate to a farther distance than a 16 inch barrel with the same bullet.

But switch to a lighter weight bullet with a lower ballistic coefficient in each of the same guns and while the velocity will increase at the onset it will actually drop below supersonic speed sooner and destabilize quicker.

Etc.

 

[xmas_asn]

When I was at LRM (Long Range Marksmanship) at Fort Campbell in 2007 we trained to shoot 700 meters with a M4 and 1k with our M14s. The LMR Instructor hit a man sized target at 912 meters with a standard M4 with a ACOG. I ranged the target myself with a laser range finder. It wasn't any super sniper move or anything. We had to spot his rounds and walk him in, but still that's a h3ll of a shot.

 

[shibumiseeker]

When I was at LRM (Long Range Marksmanship) at Fort Campbell in 2007 we trained to shoot 700 meters with a M4 and 1k with our M14s. The LMR Instructor hit a man sized target at 912 meters with a standard M4 with a ACOG. I ranged the target myself with a laser range finder. It wasn't any super sniper move or anything. We had to spot his rounds and walk him in, but still that's a h3ll of a shot.

There's no doubt you can walk a round on target at that distance. A man-sized target is not that difficult to hit at 1000 yards if you have enough shots. A friend of mine was hit a target at 1800 meters witha .45-70. He had something like 20 degrees of elevation and spent an hour doing it. You could theoretically do it with a pistol too.


There's a difference between that though, and doing it first time, every time without any feedback as to where your misses are hitting.