Bushmaster Accuracy Issues

[ZigZagZeke]

Just got off the phone with Bushmaster technical support. They were not warm and fuzzy. Guy asked me to describe the problem. Told him that my Varminter would put 2 or 3 rounds within an inch of each other, then the next round or two would be 2 inches away in some random direction. It might or might not put another round in that location, before moving another couple inches in some random direction.

His reply was “That sounds like shooter error.”

I said that I also shoot a Howa 1500 and get ¾” groups with it.

His reply, “That’s what everybody says.”

I told him that as far as I was concerned I had eliminated the shooter as a cause, and that I’d tried two different scopes with the same results. I also tried factory Remington 55 gr. Ammo and hand loads known to be accurate in another AR.

He agreed (sounded reluctant) to issue me a RMA. I want to check a couple of things first, but if I don’t find anything obvious then I’ll send it in.

On my last target on Saturday it went like this:
Shot #1: 1” high, 1” left
Shot #2: 2” high, 1” left
Shot #3: 3” high, 1” left
Shot #4: 3” high, 2” left

I came back Sunday and paid close attention to the parallax adjustment on the scope. I found that with a setting of 100 yds on the scope I got about 2” movement of the crosshairs on the target if I moved my head without moving the rifle. Adjusting for zero movement put the indicator on the scope at 150 yds(!). I need to talk to Vortex about that.

I thought I’d found the issue when the next 3 shots were in a 1” group, but then it bounced 2” up and 1” right and just kept going. I then tried a known good scope off of a competition AR. Same results. It might put 2 or 3 shots within an inch of each other, but then it would walk 2 or 3 inches.

The only thing I can see that’s not right on the rifle is there’s a small nick on the rear face of the empty cases near the ejector mark, like when they milled the bolt for the ejector slot they left a burr on the bolt face. Seems like too small a thing to cause this problem, but that’s one thing I will look at before sending this rifle off. If anybody has any clues (yes, I’m going to check the torque on the barrel nut) I’d appreciate some input. I have to say I’m not thrilled with Bushmaster’s attitude.

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[halmbarte]

1) You've checked for a loose barrel?
2) Crown looks ok?
3) How do 10 round groups look? 4 rounds is way too small a sample to see if those are flyers or if the rifle just groups that big. 20 round groups would be even better.

H

 

[ZigZagZeke]

1) You've checked for a loose barrel?
2) Crown looks ok?
3) How do 10 round groups look? 4 rounds is way too small a sample to see if those are flyers or if the rifle just groups that big. 20 round groups would be even better.

H

1. It's not obviously loose, but I don't know what it's torqued to. Was planning on removing, inspecting, reinstalling the barrel and retorquing the barrel nut.

2. There's nothing immediately visibly wrong with the crown, but I'll take a closer look with magnification.

3. 10 round groups look about 6 inches tall and 3 inches wide with no sign that it will stabilize anywhere.

Also, it seems to walk predominantly in the up direction, but the barrel was just barely warm to the touch, so I don't think it's a heat issue.

I'm also going to closely inspect the bolt face. I was too disgusted after spending all morning at the range to do much with it yesterday.

 

[halmbarte]

So, we're talking what, 6MOA out of a free floated AR?

Just to put a nail in this particular coffin, has anyone else shot the rifle? Group size?

I'd be sending it back too.

H

 

[iusmc2002]

Shouldn't you be careful doing any of your own dismantling/checking? I don't know much about it, but some companies, any attempt or actual success at taking their product apart negates any warranty. Like I said, I don't know, but I would be careful so you don't give that prick the satisfaction of sending the rifle back to you with no repairs because "it was your fault"

Good luck

 

[ZigZagZeke]

Forgot to mention I'm not the first owner and it's out of warranty. I'd gladly pay Bushmaster to make it right, and told them so. So I do want to check a couple of things first before I send it in.

 

[halmbarte]

Forgot to mention I'm not the first owner and it's out of warranty. I'd gladly pay Bushmaster to make it right, and told them so. So I do want to check a couple of things first before I send it in.

Well, you now know why the guy sold it. If it were me, and the problem wasn't disclosed before the sale, I'd be talking to the dude that sold it to me.

But I don't like to think I'm buying a orange and get a lemon instead.

H

 

[ZigZagZeke]

Well, you now know why the guy sold it. If it were me, and the problem wasn't disclosed before the sale, I'd be talking to the dude that sold it to me.

But I don't like to think I'm buying a orange and get a lemon instead.

H

I can suspect that's why he sold it, but there's no way to prove that. I've PM'd him, but he hasn't posted since Feb when he sold it, although he logged on last month. What are you going to do? Insist on shooting every gun you buy first? I'll get this mystery solved and it'll shoot to specs, one way or another.

 

[ZigZagZeke]

I came back Sunday and paid close attention to the parallax adjustment on the scope. I found that with a setting of 100 yds on the scope I got about 2" movement of the crosshairs on the target if I moved my head without moving the rifle. Adjusting for zero movement put the indicator on the scope at 150 yds(!). I need to talk to Vortex about that.

Talking to Vortex proved to be very much worthwhile. They are offering to upgrade my Crossfire ($250) to a similarly equipped Viper ($599) for $150. I think I'm going to take them up on it.

 

[iamme]

Talking to Vortex proved to be very much worthwhile. They are offering to upgrade my Crossfire ($250) to a similarly equipped Viper ($599) for $150. I think I'm going to take them up on it.

Beyond this- what mount are you using??

 

[ZigZagZeke]

Beyond this- what mount are you using??

Vortex Tactical 30mm, Extra High

See it here.

 

[ZigZagZeke]

Took a close look at the crown last night. It's hard to tell, but there might be a burr there. What's really got me interested is that there's a colored "star" pattern on the end of the barrel made by hot gasses as the bullet exits the barrel. There's a point on the "star" for each rifling groove except one! One section of the circular "star" pattern of discoloration is just blank. Maybe I found something significant?

 

[halmbarte]

Took a close look at the crown last night. It's hard to tell, but there might be a burr there. What's really got me interested is that there's a colored "star" pattern on the end of the barrel made by hot gasses as the bullet exits the barrel. There's a point on the "star" for each rifling groove except one! One section of the circular "star" pattern of discoloration is just blank. Maybe I found something significant?

Sounds like you did. The fouling pattern on the muzzle should be close to perfectly symmetrical. Deviations aren't going to be good for accuracy.

H

 

[ZigZagZeke]

Sounds like you did. The fouling pattern on the muzzle should be close to perfectly symmetrical. Deviations aren't going to be good for accuracy.

H

So I'm guessing a closer inspection by a gunsmith, and maybe a re-crowning job is in order. Or is it going to take a new barrel?

 

[halmbarte]

So I'm guessing a closer inspection by a gunsmith, and maybe a re-crowning job is in order. Or is it going to take a new barrel?

I'd at least try the re-crowning. You can always replace the barrel if that doesn't pan out.

H

 

[ZigZagZeke]

Who would be a good gunsmith to take it to locally? Anybody got a recommendation?

 

[halmbarte]

I'd call Tornado Tech out in Beaverton.

H

 

[ZigZagZeke]

Just got an email from Bushmaster Tech Support asking me to please send the gun in. That's probably what I'll do.

 

[ZigZagZeke]

Shipped the Varminter to Bushmaster today. We'll see what they have to say.

 

[TapRackNGo]

They have good CS, in my experience, and have always taken care of me.