View Full Version : Building an AR for accuracy
October 02, 2006, 09:26
Can anyone give me information regarding barrels and forends to make an extremely accurate rifle? Which is better 1/7, 1/8 or 1/9 for accuracy??
Can u order complete lower receivers without a FFL?
October 02, 2006, 09:36
lowers are the FFL item on an AR, 4473 included..
most of the target guns are using the 69-75 gr bullets, so that means the faster twist like 1/7.. many are the fatter stainless barrels, but those may not be permitted at 'military' type stock rifle matches..
free floating the barrel is mandatory, as well as target trigger group..
for what it's worth, I have a typical heavy barrel with a free float handguard, and it shoots better than I can. 1/9 twist and 69 grn Sierra Match King bullets..
October 02, 2006, 16:09
I shoot a bull barrel 1/8 twist SS mainly use 69gr to 77gr SMK in it. the fore end is free floated as para driver stated.
just some food for thought.
I asked an HK barrel maker about optimum barrel length for a 5.56 PSG-1 build. he said that anything over 20" increases drag due to the BC of the bullet (69-77smk type bullets)
pay attention to your barrel extension and bolt surface contact.
best barrels out there, opinions vary. i have 1 of 8 SS barrels from Oly that MHG and i picked out, and i shot a .217 group, measured from the outer edges.
if i was to do it again, i would go with a poly bore barrel from Mr. Noveske
October 02, 2006, 16:58
Most people are shooting either a 1:8 or 1:9 twist for extreme accuracy, for general use. A lot is going to depend on the ultimate application. Varmint shooters generally use 50-55 grain bullets, High Power Shooters use 69-80 (or 90) grain bullets, and each use a different twist. Either will shoot well with a 1:8, all other things being equal.
The 90 grain bullets are a rather specialized application for 'long range' use - 600 yards and beyond, and they require an even faster twist than 1:7 to fully stabilize.
For my money, it's very difficult indeed to beat a Krieger barrel. They ain't cheap, but in this case you DO get what you pay for. :tongue:
You'll prolly get a different recommendation of barrel makers from everyone you talk to. There are a lot of very good barrels out there. Then again, there's a lot of crap. Stay away from low end barrels like E.R. Shaw and 'no-name' barrels. They may shoot just fine - for a while. And, before anyone takes offense at me naming E.R. Shaw, I actually own one of their barrels, on a hunting rifle. It's plenty accurate enough for the application and the price was very attractive; but it isn't a Krieger (or a Shilen, Pac-Nor, Mike Rock, etc.).
October 02, 2006, 20:52
Just pick up a Rock River NM AR and your concerns are over. 1-8 twist shoots BH 69s at 200, Sierra 77 SMKs at 300 and Nosler or Sierra 80s at 600 and will clean each target at those ranges (now if I could just do them all at the same match!):D
October 02, 2006, 21:37
You could shoot a Rock River National Match, a Armalite DCM, or a Bushmaster DCM rifle (most of these shoot well) straight out of the box without any mods. These all have 1:8 twist barrels (I believe), free float systems, 1/4" and 1/2" MOA sights, and different match triggers.
Or you can build what you want. Don't get more than a 1:8 twist barrel and add a free float tube - whether you are shooting a normal service rifle upper or a match rifle upper. 1:8 twist should stabilize 223 bullets up to 80 grains. Most high power shooters like a barrel with a slightly faster twist. I am shooting a PacNor 6.5 twist barrel, I have a number of friends shooting these and Kreiger 7 twist and 7.5 twist barrels. All of us are shooting 69 or 77 grain SMKs at 200 and 300 yards, and 80 grain SMKs at 600 yards. Some guys were shooting 90 gr JLKs at 600 yards, but they were having occassional flyers that drove them crazy. Most went back to 80 SMKs.
For accuracy, get:
Good barrel 1:8 twist or better and add free float tube
Add 2 stage match trigger assembly: I recommend Rock River
Upgrade sight assemblies to match specs (smaller match aperature in rear, either 1/2 or 1/4 minute elevation and windage)
A good modification for precision iron sights is to have rear sight pinned
Good websites that shows AR mods for accuracy that build what I believe are the best service rifle uppers are:
The Wilson 1:7 twist barrels being sold by White Oak Armament have been reported to be very good shooters for the money.
October 27, 2006, 09:38
The most accurate ammo I know is the 45gn Winchester varmint at 3400 FPS.
November 07, 2006, 14:29
A very useful accessory for this purpose, especially if you reload, is the Carrier Weight System that David Tubb sells. It's essentially a flanged steel tube that inserts into the back of the bolt carrier, and it comes with both a tungsten and a stainless steel weight.
Its purpose is to slow down the bolt carrier and reduce the ejection force of the gun. It's especially useful with short barrels, as it gives gas pressures a chance to drop before initial extraction begins - the bullet actually has a chance to exit the bore before the bolt unlocks. Brass life is extended to what approaches a reasonable number of reloads, and it generally makes the rifle more pleasant to shoot.
I tested it with Federal XM193 ammo in a 16" barrel LW Colt carbine. Without the weight system, the brass was flung 8-10 feet; with it, the brass was neatly deposited 2-3 feet away. No malfunctions were experienced during test firing, either with or without the weight system.
Not inexpensive at around $50, but I think it will be a worthwhile addition to my Varmint/Target AR.
December 07, 2006, 00:51
1:7 twist white oak, krieger, or compass lake barrel, and a good float tube. NM trigger, tuned for creep and weight. That should get you where you are going. If you like the irons, get an aperture where you can swap aperture sizes, and skinny up the front sight. Anything else is just gravy. Lead weights in the buttstock to balance the rifle right at the delta ring, and it will shoot well offhand for you too.
December 07, 2006, 03:37
Had an Oly precision gun with free float and their heavy 1-8 barrel. Shot 69 grainers in the sub 3/4 inch group all day. Regret selling it. Oh, 20 inch barrel. Just plain fun to shoot for accuracy.
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