Posted: 10/27/2014 10:23:00 PM EDT
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I recently purchased 3 stripped upper receivers pretty cheap, so I've decided to do a couple different builds one of them being a 1000 yard .223 build.
I've gone through the 7 pages here in this forum and have done a search but I haven't been able to come up with the information I'm looking for. I'm newer to the AR platform and had some questions about getting the most accuracy out of an AR. I also own a Remington 700 and have done a bunch of research on how to make that more accurate but I don't see as much information on the AR platform. I do know that free floating the barrel and a great barrel are going to be the biggest gains. 1. How much does the BCG affect accuracy in the AR? 2. I know making sure that the upper and lower receiver being snug is important, but as far as internals of the the lower is there anything I should keep an eye on? If there is anything else you can think of that would be great! I think I'm going to go with a 22" +/- 2" for the barrel with a 1:7.7 or 1.8 twist. I do reload and I know that's going to be import to getting on target at those ranges. |
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Rumor is that if you can get the bolt to lock up square, without any tilt, that should help accuracy. I've heard guys trying a fistfull of bolts to see which one shoots best with their barrel (and getting some interesting results), or taking material off the lugs based on wear pattern to square up the lockout. I dont have any personal experience so ymmv. Thats the bolt part. Im not sure the carrier matters much.
As far as the lower parts, just make sure it fits the upper snug without play and that you've got a good trigger. Also make sure yor buttstock is snug and without play. |
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Although VERY few and far between, there are a handful of guys competing in F/TR who shoot ARs chambered in 223/556. That's out to 1k yards. The mid range stuff (600 yards) is more 'reasonable' for what you've got IMO.
The biggest challenge is external ballistics... that little bullet is awfully prone to both wind and deceleration (ballistic coefficient). A reeeely good barrel (the longer the better), the best fire control group you can get, the best glass you can afford, a properly headspaced bolt, a squared upper receiver, and a precise/tight fit everywhere is necessary. Size your brass to -.002. Shooting out that far with one of these autoloaders in that chambering is no joke, good luck. |
| My 20'' WOA barrel on my SPR was ordered with a "Matched" bolt specifically head spaced for the barrel. It's a lot better then hoping your match barrel shoots with your off the shelf bolt, and the best thing was they only charged $50 for the bolt IIRC when you buy the barrel. |
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http://riflemansjournal.blogspot.com/2012/03/cartridges-223-for-palma-competition.html The BCG may help at most 1/8 MOA by my SWAG. Making sure the receiver is trued straight to the barrel and having a snugger carrier-to-receiver fit can't hurt and might help. I'd get a trigger with a quick lock time and a 1:7.7 twist 24" barrel - longer than that warrants a stronger receiver. Unless single loading, you might try modifying your mags to allow a longer OAL for few rounds. IIRC some High Power guys just cut the front wall off about 5 rounds deep - M4 feed ramps sound like a good idea for that. One of my former teammates on the Junior Service Rifle team who was badass at 600 yards mentioned that she used 80gr AMAXs at 1000. |
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I built my own "precision" AR15 with reputable parts and just slapped them together. I didn't do anything special like lapping the upper receiver and didn't have a bolt specifically matched to the barrel. I don't have matching upper and lowers. In fact I only used a wedge to tighten the fit of the upper and lower. This gun still shoots an average of 3/4 moa at 100 yards and 1 moa from about 500 yards to 800 yards. This is with hand loads, but it also shot 3/4 moa at 100 yards with federal gold medal match ammo. The fgmm sucked beyond 500 yards though with major vertical stringing.
I believe all the extra stuff can be done to improve the accuracy of the AR15, but it's not going to be much. Here is an example of a 5 shot group with this rifle at 800 yards. This was the first time testing this load at this distance so my dope was a little off(I was aiming for the center of the A zone on the idpa target). I like to shoot cardboard when I'm collecting dope data so I can get an exact measurement of groups and stuff. The wind can really effect group sizes with the 223 at this distance and this was in only a 7 mph wind from my 10 o'clock with an occasional gust that caught me on the one round. 
ETA: By bolt not specifically matched to the barrel I mean it was an off the shelf BCM bcg that passed a go/no go gauge and that was it. |
There are upper & lower match sets. There are lowers with set screws to tighten against the upper. There are just accu-wedges that fit between a upper & a lower. I have an AR15 20" 1/8 Lothar Walther barrel with match bolt. With my loads that rifle will hold .75 MOA 100-500 yards, 1-1.5 MOA at 600 yards. My range is only 600 yards. I shoot my AR in F/TR, it's fun. The wind does push the bullet around more then a heavier bullet with a higher BC. My components for the load are Hornady 75BTHP, Ramshot Tac, WCC or Lake City brass, CCI 41. My upper and lower were a fitted set. Not machine together, but test fitted out of 10 for the tightest fit of that lot.
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Quoted: 1000yds need a 1:6-6.5 twist and 90 VLD's. Its pretty tough to keep 80 SMK's supersonic at 1000 even in a 24" bbl. Need to load pretty hot. |
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It's just my opinion, but if the bullets don't fit in the magazine and have to be single loaded it's pretty pointless in an AR15. Why run a semi auto in that scenario when the platform itself has accuracy limitations when compared to a bolt gun? I would run 77 grain smk bullets loaded to magazine length in the AR15. He also has a Remington 700 so why try to do everything with one gun?
I have made first round hits at 1000 yards on multiple trips testing in a wide range of atmospheric conditions with 77 smk's with an 18" barreled ar15 on an idpa target. My muzzle velocity is only 2661 fps with 23.4 grains of h4895, pmc brass, and Remington 7 1/2 primers. It's not something I would want to take to a 1000 yard competition against 6.5's, but it is very doable. Don't get me wrong I haven't always made first round hits at this distance the winds trick me some times and I certainly wouldn't expect to hit an 8" or less gong on the first shot from that distance with an ar15. I'm not familiar with long range shooting competitions because they don't have that sort of thing around here, but don't they allow a set number of sighters anyway? So essentially you are shooting sighters to get centered up and then shooting for a group trying to keep everything in the 10 ring? |
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Quoted:
I'm not familiar with long range shooting competitions because they don't have that sort of thing around here, but don't they allow a set number of sighters anyway? So essentially you are shooting sighters to get centered up and then shooting for a group trying to keep everything in the 10 ring? For F-class individual competition, sighters are usually unlimited (within the time limit of the stage. You still need to make 20 shots for score). For team matches, each shooter gets TWO sighters, and that's it. The next 20 rounds are for score. F-class puts a big emphasis on wind reading. Putting one or two rounds into a 10" target at that distance is one thing, doing it 20 consecutive times another matter entirely. It'll drive you nuts 
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1. Not at all. It's a carrier for the bolt, each has alot of built in slop.
2. It's all in the mind, according to the AMU. I use a wedge. Get a good FCG. Since you're set on shorter barrel, I won't suggest a 26", with an extended gas tube and a adjustable block |