Building an accurate AR?


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benzy2
December 12, 2010, 05:25 PM
Ok, came into some cash recently and want to get back into the AR game.

The requirements:

Accurate, mostly to be shot at paper from the bench, prone with a sling, and from a bipod. Sub MOA if not at 1/2MOA or less with the right ammo.

It will be used lightly for varmint hunting, though it won't be hiked far so weight isn't a huge issue.

Targets will typically be from 50-300 yards, though on most weekends I will have the ability to shoot to 600 yards and would like to take full advantage of that range (and therefore bullet selection).

Reliability isn't a huge deal, as this isn't going to be a rifle I take to a class and it won't be a HD/SHTF rifle. I don't want to buy Hesse, but I also don't see much reason to spend a premium for more reliability than most standard ARs show.

I'm willing to build or buy. I have assembled a lower before but have not attempted on an upper. I would be willing to build it myself, but would need to buy all of the specialty tools that go with it as well.

So now here is the combination I was looking at currently:

I plan on buying a plain flattop upper/lower combo, don't really care who's name is rolled onto the lower. I find the A2 stocks to be comfortable and would probably go with one of those. Pick up a basic LPK minus trigger. The trigger would be Geissele. Probably go with a magpul moe grip. Bolt, I'm not sure here. I don't really have much up to date knowledge on who makes a good bolt and who doesn't. It seems the "good" ones and the "bad" ones are priced similar. I would take the better one for marginal increased cost, though again, the main goal is accuracy.

For a handguard I was thinking one of the simple round float tubes, probably one with vents. They seem cheap and effective, which sounds good. For a gas block, again, not really sure if there is a difference in quality from one to another. I would probably get a gas block with rails on it, though I may go with no rails and no front sight.

The barrel is another area where I have questions. It seems there is a big jump in price from a Wilson barrel to a Kreiger/Lilja. Certainly the top tier barrels are better, but they cost quite a bit extra. Many companies using Wilson barrels seem to be able to get a sub MOA and often even 1/2-3/4MOA rifle without needing these top tier barrels. If I could know going in that a Wilson barrel would shoot 1/2-3/4 MOA with this setup, I would certainly save the money and buy it rather than a top tier. I know I stated accuracy is at the top of the list, but I really am looking for 1/2-3/4" at 100 yards. I would rather avoid a big thick bull barrel if possible, though I do appreciate the merits of a heavy barrel. If I had to pick today I would probably pick up an RRA NM barrel. They seem to cut chambers as well as any of the mid tier factories, though I hear their CS sucks. I could really go with any of the NM barrels out there though. For some reason I think they are a good blend.

So, what would you do for this type of use? What would you change? Budget is realistically around $1500, though I could go up to $2000 if there was some great leap for that extra money. At $1000 though I think I could be just about as happy as at $1500 and am not sure the extra money would be warranted over a $1000 setup and an extra $500 in ammo. I've already got the scope/optics side covered, so this is just on the rifle.

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taliv
December 12, 2010, 05:46 PM
though they are good barrels, the problem with most NM barrels is they are twisted for heavy bullets for the 600 yrd line.
you should look into a much slower twist and shoot the flat based 50 or 52g.

round handguards are a good idea as they slide better on bags/rests. gas blocks are gas blocks. good place to save money if you aren't concerned about reliability or trying to fit under a rail

wilson barrels really aren't that bad. you should get your bolt/barrel as a combo.

consider a billet upper, which is stiffer and a lot heavier than regular forged. prob not worth the extra price, but something to consider

G27RR
December 12, 2010, 05:53 PM
For $1500 I'd probably go with a LaRue Stealth upper, and then build a lower pretty much asyou describer. I was close to doing that myself when the LaRue OBR came out in 5.56 for an even $2K, so I went ahead and bought the complete rifle and came away with a sub 0.5MOA rifle right out of the box with a full factory warranty.

http://larueosr.com/lt556-18.aspx

Could I have gotten the same performance for $500-800 or so less? Mayb, but LaRue guarantees subMOA performance and includes a factory target with a five shot group verifying it. Going that route, I knew what I was getting into and didn't have to worry about getting a component that wasn't quite to spec and trying to figure out what to fix to get the accuracy I wanted. The LaRue is extremely high quality. The first target I ever shot with it is below, including some extra sight in shots. The rest were 5 or 10 shot groups. Black Hills 55gr FMJ. 1:8 will handle a wide variety of bullet weights well.

http://i1143.photobucket.com/albums/n634/G27RR/2010-11-02160908-1-2.jpg

LaRue OBR 5.56mm 18" barrel 1:8 twist with Wylde chamber
Weaver Tactical Grand Slam 3-10x40 mil/mil
Burris PEPR mount
Burris FastFire II

http://i1143.photobucket.com/albums/n634/G27RR/IMG_1058.jpg

http://i1143.photobucket.com/albums/n634/G27RR/IMG_1076.jpg

http://i1143.photobucket.com/albums/n634/G27RR/IMG_1084.jpg

http://i1143.photobucket.com/albums/n634/G27RR/IMG_1069.jpg

benzy2
December 12, 2010, 05:53 PM
Taliv,

I was planning on picking something with a 1:8" twist. Since I do plan to shoot a bit out to 600 yards I was hoping to bump up from 1:9" twist. I thought 1:7" seemed a bit much and that the NM twist of 1:8" was a good middle ground. I was planning on shooting mostly 69-77gr bullets from 300-600 yards and some of the middle weight hunting bullets for any furry targets. Is there a reason to slow down to 1:9" and 50-65gr bullets if I plan to shoot mostly 100-300 yards with say 1 in 3 range days shooting out to 600 yards? It seemed like I would be handicapping myself at much distance, though if I can get a 1:9" to stabilize a 69gr bullet I probably won't be giving much up.

rcmodel
December 12, 2010, 06:11 PM
Budget is realistically around $1500,If I had $1,500 bucks to spend I would buy a working rifle, not build one.
Specifically, one of the new Colt LE6940 Advanced Law Enforcement Carbines with the monolith handguard receiver.

I have seen a couple of gun tests, (one in the NRA American Rifleman Dope Bag) where they were shooting way sub-MOA with everything except Wolff Steel case ammo.

http://www.budsgunshop.com/catalog/product_info.php/products_id/60387

rc

taliv
December 12, 2010, 06:20 PM
if it's a range gun, sure. i misread your OP and thought you meant mostly "varmint" hunting. NM is a good profile for what you want. it's heavy enough, but designed to be shot off-hand, so it's not TOO heavy.

TonyAngel
December 12, 2010, 06:23 PM
I've done a good bit of experimenting and hunting around for good barrels over the last year or so. I've also talked to a lot of builders and barrel makers. The consensus seems to be that you really don't want to spin a bullet any faster than you need to, but on the other hand you also have to leave your options open if a broader bullet range is what you want to shoot.

If you could say that light varmint bullets are all you are going to shoot, then I'd suggest a 1:12 twist. This should do fine for bullets whose length approximate that of the usual 55gr bullets or shorter. If you also want to be able to shoot the heavier stuff, like the 77gr bullets, then you'll just about need to go to a 1:7 or 1:8 twist to accommodate bullets of this length. Since you mentioned wanting to shoot the heavier stuff, you are going to have to make somewhat of a compromise and go with the faster twist.

Keep in mind that you can't just call a builder and tell him that you want a rifle that will shoot 1/2 MOA. If you get a builder to give you an accuracy guarantee, it's going to come with a caveat, in that it will only be guaranteed to give that level of accuracy with a particular type of ammunition. I doubt that you will be able to get a rifle built that will come with a guarantee to shoot sub MOA with all types (or even two types) of ammunition.

I'd also suggest that you just buy the whole upper from a builder that is willing to give you an accuracy guarantee. You won't get the guarantee with just the barrel. Believe me. I've built several sub MOA uppers and on some of them it took a good bit of head scratching to get them shooting the way I wanted. If building wasn't a hobby that I enjoyed, I'd just hand my money over to someone that will offer an accuracy guarantee and make it their problem.

Of course, the two things that have the greatest impact on accuracy are the barrel and the ammunition. Barrels are like optics, you get what you pay for. I've seen several Wilson barrels shoot sub MOA. They are nice barrels. The difference between them and, say a Krieger, is the quality of the barrel in terms of manufacturing. The "better" barrel will likely shoot to the same point of impact from the first cold bore shot to the 20th shot after the barrel is smoking hot. Finding barrels that will do this is a big deal to me. Another consideration is how many rounds you can put through the barrel before accuracy starts to taper off due to fouling. Better barrels will go many more rounds before they foul out.

I've never regretted buying quality, within reason. This is why I'm a big fan of Nightforce scopes rather than S&B or Hendsoldt. It's also the reason that I'm a big fan of barrels like Ranier Arms, Bravo Company's SS410 and Superior Barrels. I also like Krieger barrels a lot. They are a bit more pricey than the others, but the quality shows. The downside is that they have something like a 6 month waiting list, unless you can find something that you like in their inventory.

If you are looking for a bang for your buck, maybe you should consider either one of the Rock River Predator models or one of the Bushmaster Varminter or Predator models. These shoot very well with the right load.

benzy2
December 12, 2010, 07:30 PM
I understand their is no promise of accuracy buying parts individually and that getting a complete upper/rifle from a company will give me that guarantee. That said, I don't mind working on the rifle, and honestly, that's a big part of the fun. I do reload and understand about the issues with needing proper ammo to shoot to the rifle's potential. I don't mind load testing to find the best result.

As for the Colt, it honestly isn't what I'm looking for. The rails are a big turn off. I'd much rather a smooth float tube just because I won't use the rails, they pull a premium (for an item I don't care for), and from a sling they are painful, though I guess rail covers are simple enough. Also, I'm not really looking for the cheapo collapsible stock. Too much play in the system. I'm not set on the A2 specifically, but I know I don't want the standard 6 position stock either. I have no need to shorten it up. I'd also rather a rifle length system. At the 600 yard line I think the extra barrel would make a difference. The softer cycling of the rifle length would be nice as well. It's another one of those areas where the benefits of a short barrel don't shine and the negatives of the short barrel show up. I'm not against Colt, but a carbine isn't really what I'm looking for.

supercalvin56
December 12, 2010, 07:41 PM
RRA lower with White Oak Armament varmint upper. Have WOA workover the RR two stage trigger and spend the rest on a good scope and reloading components. Done and under budget.

G27RR
December 12, 2010, 07:45 PM
If it's a dedicated long range gun, and you decide you don't want the A2 stock, consider the Magpul PRS. I use one with an AR-10 and it's nice for that type of shooting.

TonyAngel
December 12, 2010, 07:52 PM
Well, this is my build.

http://i154.photobucket.com/albums/s265/ajangelettejr/DSC_0004.jpg

It pretty much fits your description of what you want too.

Vltor MUR upper ~$200
Superior Barrels 18" 1:7 twist was ~$425 with matching bolt
Bolt carrier is a Bravo Company ~$60
The charging handle is a Gunfighter medium from Bravo ~$45.
The gas block was just one that I had laying around. Some $40 model.

Just yesterday I shot a ten shot group with all of the holes touching each other. I don't even bother taking pictures anymore since I got my load worked out. It does it with boring regularity. I did have to lap the upper to get it to shoot like that and oddly enough, I got a tad better groups when I was running the Daniel Defense upper receiver. I'm going to switch back to that when I get the urge to tear it apart and do it.

My last build was based on a Bravo Company 16" SS410 barrel and it shot the same. I just wanted to try something different that would get me a bit more velocity. I like the finish on the barrel from Superior. It's TOUGH.

What's most impressive about this barrel is that it shoots to the same point of impact whether hot or cold. Again, the BCM barrel did this too. I'm not saying that the groups don't open up a bit when you get it so hot that you could almost light a cigarette on it. I'm just saying that the point of impact doesn't shift. The group just opens up a tad bit, but nothing crazy. Barrels of this grade will usually put 20 rounds into right around an inch, which is really good. I'm not talking about shooting and then letting the barrel cool. I'm talking about 20 rounds strings. Of course, this only happens when I'm up to the task.

If all you need is just that first couple of cold bore shots, you can save yourself some money on the barrel. If you plan to be putting lots of lead down range, get a good barrel.

I don't know how much portability means to you, but I've found this rig to be a little too long for my likes. If I go with another barrel, it's either going to be a 16" or an 18" with a brake machined into the barrel. I'm a small guy and when I had the 16" barrel on it, it was a nice compact package with the stock all the way retracted and no muzzle device on the barrel.

This is what it looked like with the 16" and no muzzle device.

http://i154.photobucket.com/albums/s265/ajangelettejr/DSC_0007.jpg

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