Accuracy build help

wilkup

wilkup

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Joined
Dec 2, 2013
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Location
Cle Elum, WA
I'm newer to ARs and would like some help choosing the parts for this build that are related to accuracy.
***Other than barrel choice, what else contributes to an accurate AR?***
My goal is a 1/2MOA semi auto predator/target rifle and I'm curious what parts y'all prefer for something like this.
I'm currently considering an 18" Rainier Arms Ultramatch for my barrel, but would be open to other suggestions of similar or better quality.
I've accumulated lots of components from other builds I can utilize if y'all considered them to be quality.
I'm really struggling on barrel choice and curious what else will affect accuracy on something like this. Leverguns and boltguns are my typical purchases/builds.
Please help.
 
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I had the USMC PWS guys help me build an AR-10 on my way out a few years ago. It's a half MOA rifle with the right ammunition. They used a compound, I forget (basically jb weld), to connect the barrel and upper receiver (It's permanent). Other then the barrel, they were meticulous about the gas tube being completely straight and essentially having zero contact with the bolt. Aside from proper head spacing, that's all I'm aware of.

Check out JP Enterprise for some quality parts and barrels.
 
223 wylde or a compass lake chamber, quality barrel, and we always lapped the front reciever ring square to the bore of the upper reciever. Then used as close as we could get to 100ft/lbs of torque on the barrel nut.

The pictures are from some we built with Rock creek barrels and Rock river two stage triggers shooting factory Hornady 75 grain match.
 

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C.O. Shooter said:
AR15/10?

AR10

craddockprecision.com craddockprecision.com
Click to expand...
AR15
.223 Wylde/5.56
18'' barrel w/rifle length gas (I'm told this is a smoother system, but if a 16'' barrel w/mid length is just as good I could be swayed to the shorter barrel just to keep the rifle a bit shorter when my suppressor is attached)
My plan is to find an ELD Match from Hornady to go long for rocks and steel - 73gr/75gr/80gr
AND
A mono option from Hammer to go fast for predator control - 51gr/63gr ABs; 57gr/68gr HHTs
I have a SilencerCo Harvester EVO w/ASR compatible flash hider I plan to use occasionally with this rifle too.
 
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Recon$$ said:
I had the USMC PWS guys help me build an AR-10 on my way out a few years ago. It's a half MOA rifle with the right ammunition. They used a compound, I forget (basically jb weld), to connect the barrel and upper receiver (It's permanent). Other then the barrel, they were meticulous about the gas tube being completely straight and essentially having zero contact with the bolt. Aside from proper head spacing, that's all I'm aware of.

Check out JP Enterprise for some quality parts and barrels.
Click to expand...
I've actually been looking at the JP Enterprises silent captured spring.
 
Bert01 said:
223 wylde or a compass lake chamber, quality barrel, and we always lapped the front reciever ring square to the bore of the upper reciever. Then used as close as we could get to 100ft/lbs of torque on the barrel nut.

The pictures are from some we built with Rock creek barrels and Rock river two stage triggers shooting factory Hornady 75 grain match.
Click to expand...
Nice shooting!
Lapping things square is something that didn't even occur to me! How difficult is this to do?
Is 100ft/lbs for the barrel nut high?
I have a 2 stage trigger from Larue in the lower shared between my other rifles I really like and will likely be using one in this rifle.
 
Lapping isn't hard with access to a lathe, I had the luxury of being able to turn a mandrel to fit each upper I was working with. 100#'s is over spec and you have to be careful how you hold the upper to put that much torque on it. I have seen people rip the pin lugs off of the uppers trying to do it. We used a upper vise block with pins to hold the upper in the block, then put the whole thing in a vise, where one jaw was on the bottom of the vise block and the other jaw was on top of the actual upper, sandwiching the whole works together. The other thing is making sure the gas tube isn't being bent or hitting the carrier when everything is installed.

I have not done any testing to see how much improvement these things do, from a rifle with none of this done to one with all of it done. But every one I've built doing these things shoots better than it has any right to.
 
Bert01 said:
Lapping isn't hard with access to a lathe, I had the luxury of being able to turn a mandrel to fit each upper I was working with. 100#'s is over spec and you have to be careful how you hold the upper to put that much torque on it. I have seen people rip the pin lugs off of the uppers trying to do it. We used a upper vise block with pins to hold the upper in the block, then put the whole thing in a vise, where one jaw was on the bottom of the vise block and the other jaw was on top of the actual upper, sandwiching the whole works together. The other thing is making sure the gas tube isn't being bent or hitting the carrier when everything is installed.

I have not done any testing to see how much improvement these things do, from a rifle with none of this done to one with all of it done. But every one I've built doing these things shoots better than it has any right to.
Click to expand...
Just to clarify what you've done for accuracy... (Sadly, I don't have a lathe and will need to figure out a remedy for that)
- Squaring of receiver threads
- Over torquing barrel nut
- Getting OCD about gas tube install

What about...
- Barrel choice
- Gas system
- Bolt Carrier Group
- Recoil system
How much of a role do these items play in the accuracy of the entire system?

I'm also assuming a good trigger is important, just like any other precision firearm.
 
bamban said:
Good read.

Maximizing The AR-15: A former military armorer reveals his secrets for cutting AR-15 group sizes in half. - Free Online Library

Free Online Library: Maximizing The AR-15: A former military armorer reveals his secrets for cutting AR-15 group sizes in half.(TECH TOPICS) by "American Gunsmith"; Sports, sporting goods and toys industry Sport, sporting goods and toys industry
www.thefreelibrary.com
Click to expand...
Thanks very much for the link! Will take some time reading through it.

edit: VERY INTERESTING READ! Well worth the time. Thanks for for sharing.
 
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Barrel, barrel, barrel
chamber
chamber to bolt matching headspace
gas system regulation
forearm stiffness and interface with rest
stock and rifle balance
trigger

What makes most great AR's not 1/2 moa guns imho is they don't work with the rest and shooter well. The causes are basic things like over gassing causing rifle to bounce around. Loose parts that don't settle consistently. Forearm and buttstock not sliding well on leather. Trigger weights often tuned for overgassed bouncy gun as opposed to a smooth bag ridding rifle.

I would include these in your build:
brake
Superlative arms gas block
ALG round tube forearm
MAGPUL adjustable fixed buttstock
matched upper and lower with tension screw
Triggertech Diamond
 

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