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Old June 14, 2014, 04:30 PM   #1
Jasondcates
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Ar 15 accuracy build help.

Alright so I'm looking to build my first AR-15 I'm wanting to build it purely for bench accuracy. Being new to this there is a whole lot of stuff to know and my tiny brain can't comprehend this huge influx of knowledge. So my first question is about the barrels. I'm wanting the best damn barrel I can get. I'd love for it to be match grade 24 inch. But the problem comes to the twist ratio, from what I have read if I were to mainly fire a 223 round a twist of 1/9 would be the best correct? Another problem arrives when I start searching for a 24 inch barrel with a twist of 1/9 I can't find any! I'd like a barrel from a very reputable manufacturer that would have the pedigree needed to satisfy my need to create a tack driving son of a bitch with sub moa groups. So my main question to you is where and what company should I get my barrel from?
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Old June 14, 2014, 04:51 PM   #2
Theohazard
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My first question is why do you want a 24" barrel? The reason for a barrel that long is if you need the extra velocity for longer-range shots, like beyond 500 meters or so. But a 24" barrel won't necessarily give you any more accuracy than a 16" barrel.

Also, you want to pick your rifling twist based on the weight of the bullets you'll be shooting (heavier bullets are almost always longer, and longer bullets need a faster rifling twist). If you're doing longer-range shooting and you want to focus on bullets over 69 gr., then you might want a 1:8 or even a 1:7. But a 1:9 will be best with the bullet weights most people shoot (50 gr. - 69 gr.), and if you want to go above 69 gr., some 1:9s will even shoot bullets above 69 gr. just fine. Here's a link to a sticky about .223 rifling twists.

EDIT: I just noticed this is your first post. Hi and welcome to TFL!
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Old June 14, 2014, 04:53 PM   #3
lmccrock
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What distance? What sights?

For long distance (>600 yards), the long barrel makes it easier to load ammo to keep velocity up. Not necessary, but helpful. Palma Service rifle shooters use a 20" barrel to shoot at 1000 yards, but not a 1:9. Distance usually means heavier bullets hence a faster twist.

A 24" barrel would be useful for iron sights if you want to put the front sight near the muzzle. Does not help inherent accuracy, but makes it easier to get the most of iron sights. For scope, a shorter barrel is ok. 20" 1:9 should be easy to find.
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Old June 14, 2014, 09:30 PM   #4
Jasondcates
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Thank you for the replies guys and thanks for the hospitality! I have a retarded amount of questions so if there is one experienced fellow out there that wouldn't mind helping me out please let it be known!
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Old June 14, 2014, 09:44 PM   #5
reynolds357
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Ask away, I will gladly try to help.

For accuracy the following are most important.
1. Barrel quality (install it free floated)
2. Upper quality
3. Fit of barrel to upper
4. Fit of upper to lower

I think the reason you are not finding a 1 in 9 24" barrel is because a 1 in 7 twist would be much more useful in a barrel that length. 1 in 8 would be better than 1 in 9, but 1 in 7 would be ideal.
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Old June 15, 2014, 05:07 PM   #6
Metal god
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Yes , the reason your not finding 1-9 match barrels is because match shooters use heavy bullets that need a faster twist . If it's for an AR you will be stuck with 77gr bullets because it's the heaviest bullet that will fit in the magazine . Remember the bullet diameter is always the same so the only way you get heavier is to add length . The longer the bullet the more the back end wants to flip around in flight and become the front . That's because the there is more weight behind the center line ( length wise ) of the bullet then in front and the pressures being exerted to the tip/front of the bullet in flight makes the bullet want to flip over . The longer the bullet the more spin you need to keep that from happening .

http://www.youtube.com/watch?v=kThMXchUJ3A
http://www.youtube.com/watch?v=Z3h0pMQAFUU
http://www.youtube.com/watch?v=rj5wTsgO7ko


For the most part when talking AR match barrels your seeing 1-8 twist which is real good for the 77gr bullet most use because of the mag limitations . 20" barrel is all you will need to shoot hundreds of yards accurately - 600+ .

http://shopwilsoncombat.com/223-Wylde/products/395/

http://www.midwayusa.com/product/156...tainless-steel
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Old June 15, 2014, 05:19 PM   #7
JD0x0
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While a 24'' likely wont be any more accurate, there are advantages (and not just at 'long range') to having a higher velocity.

Less drop, less drift at all ranges. Longer range until bullets go trans and sub-sonic. Less time of flight, less time spent in crosswinds, updrafts, etc.
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Old June 15, 2014, 05:25 PM   #8
Theohazard
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Quote:
Originally Posted by JD0x0
there are advantages (and not just at 'long range') to having a higher velocity.
This is true, but the velocity advantage is much more noticeable at longer ranges when the bullet starts to slow down and drop rapidly. And especially considering the OP is talking about only shooting at 200 yards, a 24" barrel will offer almost no noticeable advantage over a 20" barrel.
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Old June 15, 2014, 08:30 PM   #9
reynolds357
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One other thing to consider is tuning a 24" AR. To keep the rifle from beating itsself to death, you will either have to find a gas system 4" longer than "rifle" length, or you are going to have to use a real heavy buffer. I am sure the parts are out there, but a 20" is the longest I have ever dealt with. I am sure someone on here can tell you the "ideal" way to deal with that problem. I am sure you could use a piston system, but I am not real fans of the pistons on precision rifles.
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Old June 16, 2014, 04:39 PM   #10
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The most accurate barrel/receiver combo you'll find is White Oak. You'll find them at the top of the leader boards of any major High Power Match.

If you want a benchrest gun then you should go the bolt gun route.

You don't need a 24 inch barrel unless you are using a bolt gun and iron sights then the extra barrel will come in handy for the longer sight radius.

Don't get hung up on a 1:9, look at the 1:8 or better yet, 1:7, they will shoot the lighter bullets as well if not better then the 1:12/1:9, but you'll have the option of using the longer (heavier) , higher BC bullets, if you want to step out there, 600-1000 yards.

I haven't seen a 1:9 that will shoot 77 gr. bullets as well as a 1:8 or 1:7, also the heavier bullets will help a great deal if the wind blows.

White Oak:

http://www.whiteoakarmament.com/xcart/home.php?cat=
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Old June 16, 2014, 07:03 PM   #11
MrBorland
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Quote:
Originally Posted by kraigwy
The most accurate barrel/receiver combo you'll find is White Oak.
Keystone Accuracy builds a terrific rifle, too. I don't shoot High Power (yet), but John Scandale is another builder highly regarded in that community. His turnaround is quite a bit quicker than WOP, too.
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Old June 16, 2014, 07:36 PM   #12
marine6680
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I have heard, all things being equal, that a shorter barrel can produce better accuracy. This is due to the shorter barrel being stiffer for a given diameter barrel. Better harmonics and repeatability...

Is that true? Well I can't tell you, it was just something I read somewhere.

I know thicker bull barrels that increase stiffness are liked by bench shooters.


Long barrels are really needed to gain extra velocity to help retain energy at longer ranges.


Another thing... Does it need to be 223/5.56?

I hear good things about 6.5 Grendel for accuracy. But I think it really shines on the long ranges up to 1000 yards.

For 5.56/223... If the ranges you want to shoot are longer, 500yds or so... Then a 1in8 twist might be a good idea. As heavier bullets are better for longer ranges, better wind bucking.

A 1in9 18 inch barrel should work great for ranges less than 500 yards.

A 18 inch 1in7 barrel and 69 grain match bullets can work well from 100yds to 500yds and maybe more if you have the skill.
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