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Posted: 10/25/2003 7:57:23 PM EDT
I am looking at getting my 1st AR-15, but would like to know what, if any, accuracy difference you all see in a 16" vs. 20" barrel? I would guess that the longer sight radius of the 20" (when using iron sights) and the slightly longer barrel length would make for a more accurate rifle, but what have you all seen from a real-life perspective?
Link Posted: 10/25/2003 8:07:25 PM EDT
I've hit the same targets at the same ranges with both my carbine and rifle. I haven't shot passed 400 meters so I can't really say if find one more accurate than another. a longer barrel will give you greater velocity for better fragmentation and longer travel, and the longer sight radius should be better for iron sights, but with a scope, I can't see one being more accurate than another under 300 meters.
Link Posted: 10/25/2003 8:08:53 PM EDT
Vinnie is correct. Shorter barrels effect muzzle velocity and not accuracy.
Link Posted: 10/26/2003 2:38:02 AM EDT
Yep, you've been told straight, bbl. length has nothing to do with accuracy just velocity. Guns & Ammo magazine did a test a number of years ago about this very thing. They took a revolver and placed it in a Ranson Rest. They started with a long bbl.(forget the length, think it was 8" or 10") and fired a group. Then they cut the bbl. back an inch at a time until it was flush with the frame. Accuracy stayed about the same thruout the whole test. One thing that can really effect accuracy is the crown on the muzzle. If you have an accurate rifle with a good crown take care to preserve that crown and you're rifle will stay accurate.
Link Posted: 10/26/2003 4:36:11 AM EDT
With irons, I find I shoot smaller groups with a 20. With optics, it makes no difference.
Link Posted: 10/26/2003 10:19:19 AM EDT
Yes, 20" barrels are more accurate....only stands to reason they would be....better sight radius and velocity.
Link Posted: 10/26/2003 12:08:43 PM EDT
Thanks for the feedback. Wasn't sure if the sight radius difference was a big factor or not that anyone has noticed. Sounds like it might be to some extent.
Link Posted: 10/26/2003 8:21:20 PM EDT
A dissipator will give you the full 20" sight radius in a 16" barrel
Link Posted: 10/27/2003 6:18:58 AM EDT
Guns with longer sight radii are [b]easier to shoot accurately[/b]. Not "more accurate."
Link Posted: 10/27/2003 6:49:28 AM EDT
Which would still make them more accurate....
Link Posted: 10/27/2003 6:53:29 AM EDT
All of the above. But all else equal , the higher velocity from a 20" means wind will have less effect on the bullet.
Link Posted: 10/27/2003 7:45:09 AM EDT
Wind drift and shooter input (muzzle velocity and sight radius from the above responses) have nothing to do with mechanical accuracy. Wind drift has to be compensated for with either barrel length. All that changes are the values. Shooter input is the limiting factor to all firearms. A person that can't shoot well won't shoot better with a different gun. Some people shoot the shorter sight radius guns better, it's a matter of how their eyes work. That doesn't mean that the mechanics of the longer sight radius don't work in their case. That is practical accuracy. Accuracy comes from repeatability. Repeatability comes from consistency.
Link Posted: 10/27/2003 7:50:42 AM EDT
[Last Edit: 10/27/2003 7:51:19 AM EDT by Not_A_Llama]
Long and short barrels should be equally precise; but their accuracies will differ at long distance. The lower velocity from the short barrel will mean that its parabola will be horizontally compressed. Proper compensation, such as from a BDC, though, will negate the difference.
Link Posted: 10/28/2003 7:18:29 AM EDT
[Last Edit: 10/28/2003 7:23:23 AM EDT by blikbok]
All being equal, a shorter barrel will be stiffer, and theoretically more precise than a longer one. I, for example, have a tuned 16" upper which outshoots my stock 20" upper, with irons and scope, with about half the group size. If you want a shorty, get a shorty, if you want a twenty, get a twenty. There will be no practical accuracy difference. There are plenty of variables more significant than barrel length. Free-floating, muzzle condition, ammo selection....
Link Posted: 10/28/2003 1:21:40 PM EDT
I have used my AR for Deer hunting the past 4 years and have shot 4 Deer in that time period, 2 with a 16" head shots at 40 & 75 yards, 1 with my 11.5" CAR upper at about 40 yards head shot and 1 with a 20" between 30 and 40 yards again in the head. I tell you what if you are a practical shooter they are all very effective.
Link Posted: 10/28/2003 1:44:24 PM EDT
Originally Posted By jem375: Which would still make them more accurate....
View Quote
ONLY with iron sights.
Link Posted: 10/28/2003 5:22:49 PM EDT
Thanks all. Sounds like barrel length isn't that huge of a factor, even for sight radius (from a practical standpoint).
Link Posted: 10/28/2003 8:48:17 PM EDT
Get the 20" if you want accuracy, if all you want to do is just shoot ammo, get the 16"....
Link Posted: 10/28/2003 11:12:18 PM EDT
Or do what I did - get both... Bought the 20" first, to wet my whistle... Then put together a 16" M4... Both shoot very well - try it, you'll like it... [sniper2]
Link Posted: 10/29/2003 4:22:59 AM EDT
As others have noted, shorter barrels are actually more inherently accurate. My own experience bears this out. Because of reduced velocity, shorter barrels will have a shorter point blank range and be effected by the wind more. The difference is pretty minor (about 4% with M193). With proficient marksmen, there seems to be no difference in accuracy due to a longer sight radius. For a first AR, I'd get the 16". If you do get the 20", get an M16A2 profile barrel. My first few ARs had 20" heavy barrels; they are heavy and unbalanced pigs. There seems to be little to no accuracy difference.
Link Posted: 10/29/2003 8:59:41 AM EDT
[Last Edit: 10/29/2003 9:12:43 AM EDT by blikbok]
I agree with Impostor: my first AR's were 20" HBAR A2s. Either go A2-profile or 16", and if you want an accurate 16", get a flattop and free-float. :)
Link Posted: 10/29/2003 2:43:05 PM EDT
My 16" Model 1 standard CAR kit is as accurate as my 20" Armalite upper...1/2moa...with the right ammo. What works great in the 20" didn't work quite as well in the 16"; I'm still tweeking that load, but I think I'm pretty much where I need to be. There is no reason to avoid a 16" barrel over accuracy questions.
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