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Geoffkoop
02-20-2007, 9:22 AM
I am building my first AR and was wondering about the Stag 5.56 16inch upper...

At what distance will this be accurate up to (approximately)?

How much more accurate is the 20inch barrel?


I know there are alot of variables that come into play just wanted some opinions.:D

luvtolean
02-20-2007, 9:35 AM
More accurate than I am.

It's not made for bench work, but my Stag hits where I point it. I am sure it's no worse than 2MOA. And probably better with good rounds.

As far as distance....that is highly dependent on bullet, load, and most of all, you.

But the idea for the M4 was that most combat occurs within 300m.

18" SPRs are good for kills at 800m, which is probably as good as the platform will get with .223.

ocabj
02-20-2007, 9:40 AM
18" SPRs are good for kills at 800m, which is probably as good as the platform will get with .223.

Without getting into a discussion on 'kill factor' or terminal performance, accuracy of .223 / 5.56 at 800 meters is questionable. 800 meters = 875 yards. Even with MK 262 ammo, which is about as hot as I would go with the 77gr bullet, the bullet will lose supersonic flight at around 750 yards in an 18" barrel.

This is based on memory. I'm too lazy to run the numbers through JBM. But I'm 95% sure that the 18" SPR barrel won't be able to keep the bullet supersonic past 800 yards with any mag length ammo.

Prc329
02-20-2007, 9:40 AM
My Stag 2h is pretty on at 100 yards. I am not sure of the groups, but it hit where I pointed all day long. I couldn't miss.

ocabj
02-20-2007, 9:47 AM
I just ran the numbers through JBM with a generous 2800fps muzzle velocity and a 77gr bullet will barely maintain supersonic flight at 850 yards:

700 1314.0
750 1242.4
800 1179.1
850 1124.6
900 1078.5

Take that data with a grain of salt, of course. I believe the JBM software defaults to the G1 drag function. I believe G3 or G5 fits modern day HPBT and VLD bullets more appropriately. Also, 2800 fps is going to be very hot for an 18" barrel. I was able to copy the published velocities for MK 262 mod 1 in an 18" barrel in my own 18" SPR and to get 2780fps, I was pushing the limits of pressure on the cases.

luvtolean
02-20-2007, 9:51 AM
Without getting into a discussion on 'kill factor' or terminal performance, accuracy of .223 / 5.56 at 800 meters is questionable. 800 meters = 875 yards. Even with MK 262 ammo, which is about as hot as I would go with the 77gr bullet, the bullet will lose supersonic flight at around 750 yards in an 18" barrel.

This is based on memory. I'm too lazy to run the numbers through JBM. But I'm 95% sure that the 18" SPR barrel won't be able to keep the bullet supersonic past 800 yards with any mag length ammo.

I am not expert enough to argue with you on the matter, and my reloading manuals don't have the data for this combo.

I am relaying what I remember reading...could be wrong.

This is the first article I found and it mentions 700m.

http://www.gunsandammomag.com/long_guns/ar15_071105/

Anyway, that's the hairy edge for the round with a .223 mag feedable OAL and in the platform. :)

Geoffkoop
02-20-2007, 9:51 AM
So if I was out pliniking, could the GUN hit a soda can at 200-300 yds?
Taking shooter error out of the equation.

ocabj
02-20-2007, 9:53 AM
Yes. Easily.

TMC
02-20-2007, 9:53 AM
Barrel lenght has less to do with accuracy and more with velocity. The 16" gun will shoot just as straight as a 20" but the bullet will be going slower. Slower bullets translate into faster drop at longer ranges which means more hold-over/hold-off which makes accurate shots tougher.

ocabj
02-20-2007, 9:59 AM
Slower bullets translate into faster drop at longer ranges which means more hold-over/hold-off which makes accurate shots tougher.

Technically, faster bullet drop doesn't necessarily make for a less accurate shot. The ballistic coefficient of the bullet is the main factor due to wind.

A 77gr bullet with a muzzle velocity of 2750 fps will have more wind drift (it will be affected by the wind more) than an 80gr bullet with a muzzle velocity of 2650 fps.

But yes, a faster bullet drop will affect the maximum accurate range of the shot.

|-007-|
02-20-2007, 10:36 AM
I shoot at a silhouette target a little further than 375 yards away (and up on a hill) and hit it maybe 25% of the time. I'm using a 16" bushmaster with an Aimpoint CompML2, so it's not the optimal setup for shooting things that far away. But my point is that I still have lots of fun shooting at things 375+ yards away because my rifle is accurate enough to hit them when I point it just right. The 16" barrel is plenty accurate for me and my surplus ammo, and I like the way it looks and feels.

Whitesmoke
02-20-2007, 11:07 AM
So if I was out pliniking, could the GUN hit a soda can at 200-300 yds?
Taking shooter error out of the equation.

With good ammo...yes.

With regular mil-surp ammo....you would miss a lot. Especially at 300 yards.

Morales
02-20-2007, 12:06 PM
Lets also keep in mind the twist of rifling along with barrel length, and burn rate of powder. Those effect accuracy as well. That is why the M4 carbine is often compared to the AK47 accuracy wise. At least in military AR15 barrels, the powder burns at a certain rate with a certain twist of rifling. The M16 is accurate because the round it "tuned" to be optimum with the rifling and time in the barrel. So if you are hitting things really well at 300 yards, with a 16 inch barrel that is great, but it seems to me that with such a wide variety of civilian loads, it would be hard to find one that is really optimum for a 16 inch barrel with a 1:9 twist of rifling? Am I making sense? Or am I mistaken on these points?

bwiese
02-20-2007, 12:12 PM
Many things go into bbl accuracy.

Since you're using a chrome-lined bbl w/milspec chamber, those are the bbls you should compare against. (Stag 20" bbls are *not* chrome-lined.)

Your Stag M4 bbl is a lighter profile and is not free-floated. A stiffer barrel and that is free-floated will help accuracy. (The stiffer the bbl the less likely free-floating is needed at least for shooting from a benchrest, if you can benchrest near the chamber area right after the receiver and not toward the front of the bbl)

My Bushmaster M4 and my Bushmaster Dissipator are both 16" bbls, chrome-lined with milspec 5.56 chambers. The Dissy bbl is, however, heavier/thicker, and shoots very nicely - more so than the 16" Bushy bbl.

TMC
02-20-2007, 1:26 PM
Technically, faster bullet drop doesn't necessarily make for a less accurate shot. The ballistic coefficient of the bullet is the main factor due to wind.

A 77gr bullet with a muzzle velocity of 2750 fps will have more wind drift (it will be affected by the wind more) than an 80gr bullet with a muzzle velocity of 2650 fps.

But yes, a faster bullet drop will affect the maximum accurate range of the shot.

You're correct, I should have prefeaced the statement with "for a given bullet weight" and also added that both barrels being equal in specifications with the exception of length

anonymous
02-20-2007, 2:53 PM
I am building my first AR and was wondering about the Stag 5.56 16inch upper...

At what distance will this be accurate up to (approximately)?

How much more accurate is the 20inch barrel?


I know there are alot of variables that come into play just wanted some opinions.:D

I routinely shoot .223 inch one-shot groups with mine from distances of up to 800 yards.

Another thing to consider is that the 20" barrel will emit less noise and flash. Also, it may look less "evil" to the authorities. The extra 4" inches translates to something like an addition 200 fps, over a base of about 3000 fps. Thus, as you can imagine, its not going to make much more than a tiny difference at normal shooting range distances. Personally, I prefer the look of the 20" though.

But with the Stag, you have more ordering options with the 16". Therefore, if you don't prefer the aesthetics of the 20" or the lower noise or slightly improved accuracy, I'd go with a 16" without a carry handle or sights and then stick on an ACOG or scope.

-hanko
02-20-2007, 3:17 PM
I am building my first AR and was wondering about the Stag 5.56 16inch upper...

At what distance will this be accurate up to (approximately)?

How much more accurate is the 20inch barrel?

I know there are alot of variables that come into play just wanted some opinions.:D
It's a little hard to believe that you've selected a cartridge without knowing how far out it'll work;)

Accuracy will depend much more on the shooter than the gun.

From http://www.fas.org/man/dod-101/sys/land/m16.htm...

Maximum range :3,600 meters Maximum effective range:
Area target: 2,624.8 feet (800 meters)
Point target: 1,804.5 feet (550 meters)
Muzzle velocity: 2,800 feet (853 meters) per second
From a 20 inch barrel, unclear as to 55 or 62 grain ammo but both are specified depending on barrel twist.

A carbine will have the same accuracy, but you'll see larger groups due to the shorter sight radius.

You should be able to hit a pop can as far out as you can see it...if not, buy more ammo & practice more.:D

Chromed lined v. unlined barrels won't get you much until past 300 yd., assuming you can hit what you want at that range...more a matter of how long the barrel can go without cleaning. If it's a paper-puncher, you don't need a chrome lined barrel.

-hanko