Question for the AR Guys

[jepp2]

I'll get in trouble for this, but how did you measure these groups?

Outside to outside of the furthest apart shots (very edge of the hole) - the bullet diameter. Is there a better way?

So for example on the fouler group I measured .367 + .224 = 0.591"

 

[butchlambert]

Well, it appears that the group (1st) is 4 bullet holes wide as does the second.
Your shooting looks pretty good though.

 

[243Mendoza]

check for a carbon ring in front of the neck portion of the chamber.

 

[people]

One thing to look at is your ammo. If you are shooting up some ammo that is older it might not be performing as well as it did when it was fresh.

 

[akajun]

I don't see a free floating type handguard in your buildup. Maybe you forgot to mention it but if not that is probably the biggest accuracy issue in an ar.
Next thing to check is gas tube alignment. Simply look at the end of the gas tube and make sure its centered in the upper, next, disassemble the bolt then take the charging handle and stripped carrier with Key and insert them in the upper, feel for dragging on the gas tube. you may have to turn the barrel nut one way or another or bend it up or down. There will always be some dragging you can feel but it should not be much.
Also make sure that if you do have a FF handquard, that nothing is touching the gas tube inside the handquard. A buddy had a stick on wheel weight come loose from his NM ff tube and wedge itself between the tube and hangquard. He started getting off call shots at 600, he discovered the problem after the match.

That little comet tail shouldn't cause any accuracy problems, hell Ive got a Krieger with over 5K rounds on it right now, the comet tail is probably about 1" long or longer, I shot a 9x clean with it the other day.

 

[akajun]

Also for your loads with 77's try these. If they don't work then it is your barrel.
varget, 24.1
rl 15 24.1
8208 23.1-23.2

with 69's
varget 25
rl15, 25
8208 23.5

also try using a lee factory crimp die for a light crimp. I find it gives me better accuracy and cycling on my short line ammo.

 

[joshb]

I think you’re shooting great, given it’s an AR. I have a stock Rock River carbine that shoots an inch on a good day. I bought a Stag Model 6 (I think. I’d have to dig it out to be sure, but it’s the Varmint heavy long barrel set up.) It’ll shoot a half inch when I really work at it. I tried a few different loads in it and I decided that it wasn’t going to shoot any better. It’s fun to shoot and the youngsters love it but if I want small groups, I grab a bolt gun.

If you want to try some Sierra 77 OTM, pm me your address and I’ll send you a handful. I bought a bucket full. Too many for my lifetime, I’m thinking these days.

 

[Knotwild]

Here's the build: Krieger 1-8 DMR barrel; Rock River Arms Matched Flat Top Upper & Lower receiver, JP Enterprises adjustable trigger, SLR adjustable gas block, Magpul PRS stock, Hogue grip, Leupold BR 24X scope, should equal in my thinking 1/2 MOA with my good hand loads. What I've been getting with good hand loads is about 1 MOA. So, am I expecting too much from this set up? I am 70 years old and I don't have any buddies. I out lived them all.

I'm not saying your bench manners are bad, but I greatly reduced group sizes with my AR by paying attention to details. I was using a rear bag and an old Witchita front rest and getting fair groups. I finally tried to refine my shooting by using a paper plate to allow the forearm to slide uniformly in the front rest and not using the rear rest. My groups got much better because I lost some vertical dispersion which I think occurred due to gun not recoiling consistently.

Just something simple and easy to try and see if it helps.

 

[Pawnee Bill]

I'm not saying your bench manners are bad, but I greatly reduced group sizes with my AR by paying attention to details. I was using a rear bag and an old Witchita front rest and getting fair groups. I finally tried to refine my shooting by using a paper plate to allow the forearm to slide uniformly in the front rest and not using the rear rest. My groups got much better because I lost some vertical dispersion which I think occurred due to gun not recoiling consistently.

Just something simple and easy to try and see if it helps.

Let me see if I can answer everyone's questions on my AR not JEPP2's:

Barrel: Krieger 22" DMR 1-8 twist Wylde chamber
Upper & Lower Rcvr: Rock River Arms Matched Set
Trigger: JP Enterprises 2 stage set at 2lbs.
Handguard: Armalite Free Floating
Gas Block: SLR Adjustable--Adjusted
Buttstock: MagPul PRS
Scope: Leupold BR 24X
BCG: Fail Zero
Bolt: Fail Zero
Magazines: PMag 10 rd
Muzzle Brake: Surefire SOCOM
Everything tightened & secure

My best load has been: Lapua 223 Match brass, CCI BR4 primer, 69 gr SMK, 22.0 gr H322 @ about 2800 fps.

I am shooting from a 21st Century Model 1000 LP rifle rest.

With all this one would think he would be able to print 1/2 MOA all day long.

Thanks for all the inputs, but my money is on a bad barrel and I think this was done when they drilled the gas port hole but didn't know till it was too late. If a little copper or a little carbon can affect barrel accuracy I would surely think this tear in the barrel has to be a factor. Any way, new Bartlein barrel on order from Compass Lake Engineering and we will try some more. Thanks again!!

 

[Knotwild]

Can I have your Krieger when you quit with it?

 

[Pawnee Bill]

Can I have your Krieger when you quit with it?

It's already spoke for, but if he changes his mind I'll let you know.

 

[Knotwild]

It's already spoke for, but if he changes his mind I'll let you know.

Thanks. I know it must be frustrating to cover all the bases with good equipment/parts and then have poor results.

 

[MikeMcCasland]

I know you've got a new barrel on order, so this is probably too late.

That said, how much clearance do you have between that SLR gas block and the FF rail? Those adjustable blocks are slightly bulkier than the standard ones, and I've had an SLR block make contact with a FF rail on recoil that gave me major fits on an AR10 build. If you can apply torque at the muzzle end of the barrel and get the block fairly close to the rail, that might be your issue.

I will say your gas port appears to be drilled correctly (it's centered within the groove), and the erosion is 100% normal/expected; they all do that as you put rounds down them.

Good build BTW; solid components.

 

[Beau]

That's really not too bad of shooting. About the best I've ever been able to do off a bench with an AR is about 1 1/4 MOA for 10 shots.

 

[tomswede]

Seems that boroscopes probably creates as many problems as they solve. I would say get some Sierra 77’s and R15 or Varget and go and shoot, 3/4 MOA is good accuracy for most purposes for an AR. My Kreiger 7.7 twist from White Oak shoots great with 23.5R15, so has a handful of other barrels. Sierra 80’s work well at 600