Home Forums Hunting & Shooting AR and Tactical Rifles Accuracy issue

Picked up a new Windham Weaponry Varmint Exterminator. Tuned the trigger to 2lbs, dropped in an Accu Wedge, mounted a new Leupold and set out to working up a load. Rifle is 1/8 twist so started with Hornady 68 and 75 bthp's. I've loaded '335, Varget, Tac, '15 and H4895. All powders group the same 1.5" or so @100 with the first manually loaded round going off by itself followed by shots 2-5 creating two good two shot separate groups. I can live with the first round issue, it's not an uncommon issue in my experience, but never seen an AR split the remainder of the group into two separate groups. The rifle looks like it wants to shoot, shots 2 and 3 will be touching as will shots 4 and 5, they're just separated. Where to begin troubleshooting?

odd. make sure mounts are tight, check the parallax in the scope, try another scope does not matter if its new, scope still could be bad, are you using one type of brass or is it mixed brass, could just be a bad barrel seen that as well. First guess is parallax your not putting your head in the same place.

Could be a number of issues. The most common being the shooter getting use to shooting a gas gun. Another could be a neck tension issue when you are resizing the cases. Check what jimmyp said above also, loose mounts and parallax issues can really screw up your groups also.

paralax is an easy test. set the rifle up in a solid unmovable rest, pointed at a 100 yard target (I assume this is your range), move your head up and down side to side without touching the rifle looking thru the scope, if the reticle moves relative to the target you got it figured out. Zeiss sent me a conquest 2.5-8 x 32 one time with a 50 yard paralax setting, some of the Leupolds used to be set for 150 yards or you just could have a lemon if your mounts are tight. Good place to start anyway. If an AR in 223 does not shoot SMOA with hand loads and a decent scope something is sure wrong.

Here's a photo to illustrate the issue. RL-15 and 68 BTHP @100 yards. Shot prone off front and rear sand bags. Cheek weld is soild, (AR's/gas guns not new to me), scope mount and rings are farmer tight. Will have a look at paralax/switch scopes and try a different batch of brass.

Try a different bullet

69 Matchking



70 Berger



75 Hornady



Small sampling of whats been tried, any other ideas?

Yikes! mine don't throw first shot wide, don't know why. Second that is pretty bad for an AR15, if not paralax then its the barrel. What type of scope mounts.

Windham sent a pre paid shipping label for the upper, the first thing their gunsmith suspects is barrel nut tension. Gonna swap out the scope and run a different batch of brass through it real quick before sending it back.

Yep, glad they sent the shipping label, been there and done that. If they don't have it back to you in a month then they are scratching their heads... tell them you want your money back.

Leupold MK2 IMS.

I'd be curious what Windham comes back with - I have the same rifle. I started out shooting 68-75 gr match bullets and wasn't impressed. Switching to lighter varmint bullets (50-53 gr) made a big improvement, so I haven't pursued it any further.

I'll keep you posted. Mine did better with the Nosler 60g B.T. and the Sierra 65g SBT. Defeats the purpose of rifle with a 1/8 twist rate for me though, I bought this model specifically for shooting the heavies.

The 77 SMK's have been the most accurate in all but one of mine, 77 NCC comes up next. I never could get the 75 BTHP's to impress me but Rost said they liked medium loads.

I could send you some 77's if you can't find any.

Rifle back from Windham today, test target that was included mirrored my exact issue, 3 here 2 there on 5 shot groups. They said they used Hornady 75 grain loads and ugly group or not it was just over 3/4 inch so its well within their standards.

Hmmmmm.

Get a local guy that knows what he's doing to pull the barrel, check to be sure the receiver is square, and retorque the barrel nut. Looks like a loose barrel.

Heres the factory test target, they obviously found the same issue I complained of. It's ugly as hell having a group cut in two like that, but on the other hand it is roughly 3/4 MOA @100 yards, not sure if I should be complaining, definitely looks to me like the rifle wants to be accurate, just some small bug in there somewhere. Gonna pick some AR gunsmith brains come Monday. I feel for $1100.00 Windham could have done better in the customer service dept, I'm sure if the rifle had belonged to the Windham employee who looked at mine there would have been a little more time invested than throwing 5 rounds down range and caling it good.

I am assuming those are .25" squares. If those are .5" squares I would consider that a little over an 1" group. The 2 on the left are a less than .5" group and the 3 on the right are a less than .75" group but other than that it is 1" or better anyway you cut it to me.

If you are getting a first shot fly, it's a chambering issue called "bolt over run". There's too much clearance between the barrel face and the lug seats in the barrel extension. The cure in ARs is to get a new barrel.

You can get a feel for the problem by inserting the bolt into the barrel and twisting it to lock. There shouldn't be more than about 3 thou of forward-backward play in the bolt.