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eighteenninetytwo
04-30-2010, 4:09 PM
I have a 20 inch heavy barrelled AR - 1:7 twist.
I have a RRA scope mount on it and a bog standard scope (Bushnell hunting scope designed for .308).
My accuracy with this set up was pretty ropey - I'm getting 2-3 inch groups at 100 yards from the bench.

The rifle has a match trigger and foreend which allows a free float barrel and was set up to get less than 1 MOA by a well thought of builder.
it's i chambered in 22.3 as opposed to 5.56
I'm pretty certain this isn't me either because I get 2 inch groups with irons on my Lee Enfields and one inch groups with My No'4 T sniper rifle.
I'm certain it's not the scope.
Scope mount - it's a cheapy I think but seems solid enough.
Rifle - no reason to suspect that.
Variables
I was using 55 grain American Eagle ammo - is this too light maybe? or should I just expect this level of accuracy from this ammo?
Alternatively is it just because the set up and the rifle is new (less than 200 rounds through it altogether)
Any ideas - it's my first AR.

CSACANNONEER
04-30-2010, 4:14 PM
Try different ammo. Personally, I'd recommend reloading and experimenting until you find the perfect load for your rifle. But, if you don't want to do that, try some different brands and types of ammo.

reidnez
04-30-2010, 4:14 PM
2-3 MOA is perfectly adequate for a service rifle and its intended purpose. I'll accept that from any weapon unless I'm actually going to shoot it in a match, or possibly hunt varmints. That is minute-of-bad-guy, or minute-of-coyote. In other words, good enough for most any practical purpose. If you want better than that, it is easier (and cheaper) to start with another platform which has higher inherent accuracy to begin with. There are plenty of bolt guns these days that shoot around 1MOA out of the box, with good ammo, for under a grand. Put a few hundred bucks of work into them, and work up good hand loads, and you can cut that in half.

It's also quite possible that your ammo is the limiting factor--regular factory plinking ammo in the finest match rifle is not going to shoot much better than the same ammo in an ordinary service rifle. You can't make good wine from bad grapes.

Noobert
04-30-2010, 4:16 PM
cheaper, easier to test different ammo

dlkk
04-30-2010, 5:04 PM
Try match grade ammo
You cant expect sub MOA groups with ammo that cant shoot sub MOA.

killshot44
04-30-2010, 6:52 PM
You may not get MOA out of that rifle using less than 69gr. The 1/7 twist is awfully fast for 55gr. I've seen a number of guys banging their heads over your dilemma. They solved it by going heavier.
I would try a box each of 69, 72, 75, 77gr (of quality ammo) to see what it likes.

Cody
04-30-2010, 7:01 PM
It's the ammo. Try some V-max (40gr-60gr) or Match bullets (69gr-77gr) and you'll see better results.

-Cody

3GunFunShooter
04-30-2010, 8:41 PM
+1 on the heavy bullets. My JP 18" 1/8 really likes the 77gr Black Hills match.
1.25" groups at 300 yds.
My ASI Mini 14 18" 1/9 likes the 69gr Black Hills, red or blue box.
Trying to get a load worked up that will match the 77Gr Black Hills.

eighteenninetytwo
05-01-2010, 6:54 AM
Thanks folks
Snag is I don't reload - so I'm stuck on expensive ammo which is a blow as I got the AR to shoot ammo cheaper than the .303 brit I otherwise use. Dammiittall!

fonionrings
05-01-2010, 10:59 AM
+1 on the ammo.

American Eagle, PMC, non-match ammo I've put through my 18" SPR have resulted in unsatisfactory groupings (2-4moa). Tried a few different match grade rounds in different (heavier) weights, all shot 1moa tops.

foxtrotuniformlima
05-01-2010, 12:10 PM
Get a box of Federal Gold Medal Match w/ 69gr SMKs. Should run you about $30. Shoot that. If the groups don't shrink, then there is something wrong with your build ( headspace, chamber, crown, etc ). I'd start at the muzzle end and work back.

Mute
05-01-2010, 1:15 PM
What you need to do is to try some match quality ammo just to answer the question as to whether the hardware itself is capable of the accuracy you want. If it does, then you can still shoot the cheaper ammo, but you need to know that it won't give you sub MOA accuracy. That's just reality. If the match ammo doesn't do it, then I'd look into the scope mount. Just because it seems solid doesn't necessarily mean it is or that your scope is properly secured to the mount. Good luck.

RawImpact
05-01-2010, 5:17 PM
Your ammo is your problem

55gr with a 1-7 is way too light

62 minimum

telcolineman
05-01-2010, 6:12 PM
I agree with Raw, 62gr or heavier ammo

slappomatt
05-01-2010, 7:15 PM
I have heard loads of stories of people with 1/7 twist that love 40 grains and other oddities. every barrel is different. your problem is most likely cheap ammo as the problem. reloading isn't that hard might want to look into it. I would try black hills ammo in several different weights. they even offer reloaded ammo for a lower price.

also I find it is ALOT harder to get a semi rifle to shoot well compared to a bolt gun. I have a remington 700 that would shoot circles around ANY of my AR's and I have built several "match grade" AR's with just about everything you can do for accuracy. The platform just wasn't designed to be a bench gun.

having said that 2moa with black hills is pretty darn good!

killshot44
05-01-2010, 8:23 PM
A big +1 on the Black Hills ammo for non-realoders. The Blue Box remanufactured stuff shoots brilliantly.

Cheaper (and in your case, lighter) ammo can make you pull your hair out!

Parajeff71
05-01-2010, 10:41 PM
Your ammo is your problem

55gr with a 1-7 is way too light

62 minimum

Beat me to it.

neuron
05-01-2010, 10:50 PM
Your ammo is your problem

55gr with a 1-7 is way too light

62 minimum

I thought it was the other way around...i.e. that heavier bullets stabilize better with slower twist-rates than the 1:7 of the original M16 Mattel Toys...so that a 1:9 twist would be better for the heavier bullets than a 1:7 twist... I haven't looked this up; I'm just going with what I've been told.

Sheldon
05-02-2010, 4:12 AM
Try Hornady's 55 grainers. They are better quality than the American Eagle. My Colt 1/7 barrel really liked the 60 grain hollow points I reloaded for it. Is your upper a flat top or is the mount on carry handle upper? Reason I ask is I had a scope on my standard carry handle upper and without a cheek piece and I shot it worse than with the iron sights due to a horrible cheek weld.

pyromensch
05-02-2010, 7:04 AM
i believe that the original m-16/ar-15 's had a 1:12 twist not a 1:7

eighteenninetytwo
05-02-2010, 9:34 AM
Next weekend then I'm off to the range with some a few different 62 or higher grained bullets. Will report back then.

garuda7
05-02-2010, 10:34 AM
I can almost guarantee it's the ammo. 2-3 inch groups is pretty much standard for 55 grain standard factory ammo. If you want tight 1-inch groups, you're going to have to purchase heavier 69 or 77 grain "match" ammo. Try black hills ammunition, that stuff will get you the groups you desire.

I have a 20 inch heavy barrelled AR - 1:7 twist.
I have a RRA scope mount on it and a bog standard scope (Bushnell hunting scope designed for .308).
My accuracy with this set up was pretty ropey - I'm getting 2-3 inch groups at 100 yards from the bench.

The rifle has a match trigger and foreend which allows a free float barrel and was set up to get less than 1 MOA by a well thought of builder.
it's i chambered in 22.3 as opposed to 5.56
I'm pretty certain this isn't me either because I get 2 inch groups with irons on my Lee Enfields and one inch groups with My No'4 T sniper rifle.
I'm certain it's not the scope.
Scope mount - it's a cheapy I think but seems solid enough.
Rifle - no reason to suspect that.
Variables
I was using 55 grain American Eagle ammo - is this too light maybe? or should I just expect this level of accuracy from this ammo?
Alternatively is it just because the set up and the rifle is new (less than 200 rounds through it altogether)
Any ideas - it's my first AR.

phish
05-02-2010, 4:17 PM
55 GRAIN BULLETS ARE NOT TOO LIGHT TO SHOOT OUT OF 1:7 TWIST BARRELS! USE QUALITY BULLETS/AMMO SPELLED WITH A "Q", NOT A "K"!

:banghead:

neuron
05-02-2010, 6:31 PM
i believe that the original m-16/ar-15 's had a 1:12 twist not a 1:7

My mistake, you are correct about the 1:12 early barrels. I think there is some confusion about the relationship between twist rate and bullet weight...maybe bullet length is the more critical parameter.

Most of the recommendations I've found say that "lighter" bullets in a given caliber stabilize better with faster twists.

The current preference seems to be for 5.56/.223 barrels rifled in 1:9, presumably because these better stabilize bullets over 60gr. I suppose this is a "compromise."

GutPunch
05-02-2010, 7:03 PM
Your ammo is your problem

55gr with a 1-7 is way too light

62 minimum

Please stop spreading FUD: http://ammo.ar15.com/ammo/project/perf_twists.html

Mute
05-02-2010, 9:27 PM
55 gr. ammo is not too light for a 1-7 twist. Your problem is most likely because you are not using match quality ammo.

j1133s
05-03-2010, 11:48 AM
I have a 20 inch heavy barrelled AR - 1:7 twist.
I have a RRA scope mount on it and a bog standard scope (Bushnell hunting scope designed for .308).
My accuracy with this set up was pretty ropey - I'm getting 2-3 inch groups at 100 yards from the bench.

The rifle has a match trigger and foreend which allows a free float barrel and was set up to get less than 1 MOA by a well thought of builder.
it's i chambered in 22.3 as opposed to 5.56
I'm pretty certain this isn't me either because I get 2 inch groups with irons on my Lee Enfields and one inch groups with My No'4 T sniper rifle.
I'm certain it's not the scope.
Scope mount - it's a cheapy I think but seems solid enough.
Rifle - no reason to suspect that.
Variables
I was using 55 grain American Eagle ammo - is this too light maybe? or should I just expect this level of accuracy from this ammo?
Alternatively is it just because the set up and the rifle is new (less than 200 rounds through it altogether)
Any ideas - it's my first AR.

Anyway, your American Eagle ammo (which I've never shot,but have lots of experience w/ other cheap 55gr ammo) should give you 1.5-2" groups at 100yds easily. So, I don't think it is your ammo.

200 rounds should be enough to break in a barrel. Is your barrel stainless? If so, you should have followed some break in routine. So, I don't think it is due to new barrel.

You've got a heavy barrel, which is good since you should test group on a warn barrel and likely you were doing so w/ a HBAR.

So... Maybe damaged barrel/ chamber, Or just the obvious loose optics mount?

ar15barrels
05-03-2010, 1:23 PM
I'm getting 2-3 inch groups at 100 yards from the bench.
I was using 55 grain American Eagle ammo - is this too light maybe? or should I just expect this level of accuracy from this ammo?

The bullets are not too light, but the bullet QUALITY is lacking.
The reason people associate higher weight bullets with being more accurate is that the heavier weight bullets such as 69gr, 75gr, 77gr and 80gr are all match grade bullets while the 55gr bullets are FMJ blasting fodder.

2-3 moa is exactly what you should expect from blasting fodder, regardless of bullet weight.
There are crappy 62gr bullets as well and they will shoot about the same as the 55's do.

Buy yourself a box of Federal Gold Medal Match ammo with the 69gr Matchking bullets and I bet you are pleased with the groups you get.

killshot44
05-03-2010, 1:47 PM
The bullets are not too light, but the bullet QUALITY is lacking.

Buy yourself a box of Federal Gold Medal Match ammo with the 69gr Matchking bullets and I bet you are pleased with the groups you get.

You contradicted yourself. Of course 69gr will take the 1 in 7 twist better...that's what we're saying....;)

ar15barrels
05-03-2010, 1:57 PM
You contradicted yourself. Of course 69gr will take the 1 in 7 twist better...that's what we're saying....;)

No, the MATCHKING BULLETS will be more accurate.

You could even shoot 52gr Matchking bullets through the 1:7 and get much better groups than the 55gr american eagle ammo.

mif_slim
05-03-2010, 1:57 PM
OP: I had the same results, but I understand that this AR was made for "combat" not accuracy so I left it at that. Im getting 2.5-3" MOA with 55gr's too, reloads. The same reloads shoots sub-moa with my other AR with 1:9 twist so Im not surpirsed of what your getting. But as many have said, try heavier grain or match ammo and you should get better results.