[Caleb C]

Well, I've decided to build an AR. I'm pretty well set on how I want it to come together. I do have some questions about barrel length though. The rifle should be relatively light and easy to handle. I'd like to make head shots on the occasional deer inside of 250 yrds but it will mostly be used as a general purpose rifle. Long range beaver kills, home defense, plinking, and zombie apocalypse type situations. The military claims combat accuracy out to about 500 yrds with the carbine. Will the 16 inch barrel really provide me with the accuracy that I'm looking for or should I step up to a 20 inch barrel?

 

[M1GarandFan]

I've got a 20" AR and a 16" AR and the 20" seems more accurate to me, but that could just be me.

 

[RON55]

16 or 20 in. BARREL

I am also going to start on building a AR 15 on 7.62x39 platform and thinking about a 20 inch barrel. but like the shorter 16 inch. Going to start hunting wild hogs. Need input on 16 or 20 inch barrel.
No more than 150 yard shot.

 

[miker84]

You're going to get a lot of opinions here. Heres mine.

I have a couple of 5.56 16" AR's and they are good to 200yds (at my skill level) for plinking and varmints. They can reach 300, but I'd only try to punch paper at that range.

My next build will be a 6.8, or 300BLK in a 16". They'll take deer inside of 200 (my comfort zone) and can reach beyond 300 and still have knockdown power and accuracy. A longer barrell doesn't do much for you in those calibers.

After that, I'll build a 5.56 hbar 20" with a twist rate for heavier bullets. The 16" does all I want, but the 20" can hold its accuracy a little longer and doesn't need a flash hider. I know guys that regularly take does with one of these and a Barnes TSX, but these guys are deadeye shots and they only take deer inside of 100 with that round.

Now I'll go put on my flame suit for the dissenting opinions.
:shtf2:

 

[Caleb C]

OK. May be my goal of 250 yrd headshots is a little too ambitious. Let me ask this a little differently. What would be a reasonable range for headshots using heavy bullets in both 16 and 20 inch barrels when accuracy, velocity, and bullet momentum are considered?

 

[nonnieselman]

We have taken deer out to 350yds with a M4 barrel and 55gr FMJ 5.56 rounds.

IF your gun can hold 1moa or better you "should" be able to take deer head shots out to 300yds in theory.. We shoot for the heart/lungs or high neck and with a well placed shot they were DRT's.

 

[bubbat]

We have taken deer out to 350yds with a M4 barrel and 55gr FMJ 5.56 rounds.

IF your gun can hold 1moa or better you "should" be able to take deer head shots out to 300yds in theory.. We shoot for the heart/lungs or high neck and with a well placed shot they were DRT's.

What Nonnie said. ^^^^

Didn't I read somewhere that the 6.8 was designed for a 16" barrel, that you gain nothing going to a 20"?

 

[nonnieselman]

Yep.. on a 6.8 you dont gain very much FPS goin over 16"..
can get 3000+fps with a 85gr no problem thru a 16" spec II chamber

 

[Caleb C]

What about with a 5.56. Are there considerable velocity gains by adding 4 inches of barrel?

 

[nonnieselman]

Yea it helps a 5.56 out a good bit..


"I chronographed 55 gr federal FMJ:

3140 fps in a 20"
2850 fps in a 16"

RP & WW were also pretty much the same plus or minus 20-30 fps."

 

[Caleb C]

+300 fps is almost enough to make me go for the 20 inch and forget about the 16 all together. That sort of goes against my first requirement, though. It must be light and easy to handle. Worth the trade off? May be.

 

[nonnieselman]

only thing thats really gonna change is your drop and wind drift with a slower round. I have a DPMS 16" bull barrel and it gets pretty heavy.

http://www.midwayusa.com/viewProduct/default.aspx?productNumber=519542


It shoots pretty good, ive gotten .25" groups at 100yds with 55gr Vmax loaded with Varget in LC brass.. only shot it a few times out to 600 and 800 but i was running out of mildots

It shoots my 69gr PPU Match loads packed with H322 at 2850fps, and they are 3080 thru my Stevens 223 22" barrel.

 

[smoffett]

I suppose you could go 20" non-heavy barrel. That keeps your weight down and still gets you the velocity gains of the extra 4 inches. If you shoot until the barrel's hot, well then the accuracy might suffer.

 

[osucowboy8]

All of mine are 16" and they are plenty accurate for my skill level (or lack thereof). YMMV.