How bad is this crown?

[Popapi]

Pressure/Gases CAN'T be uniformative around that crown have it redone!

 

[new shooter]

Ho maid the barrel ?

 

[WildRose]

I've been trying to figure out why I can't get my AR-15 to shoot. Basically the best 5 shot group I can muster is around 3". I posted about it here a couple months ago:

http://www.longrangehunting.com/forums/f19/ar-15-accuracy-help-40596/

The more I read the more I see that "everyone" with an AR-15 seems to get pretty good accuracy (< 1 moa). I have access to a boresope at work, so I decided to take a closer look at the barrel to see if anything jumped out at me. I didn't find anything inside the barrel that stood out (although I'm no professional), but below is what the crown looks like. Now again I'm no gunsmith, but this crown looks like a rat chewed on it.

I don't know exactly what a "good" crown should look like, but can I assume that this is not it?

Do you think that this could be my source of inaccuracy?

Horrible; it looks like chunks are flying off when you shoot or else the crown job from the factory was utterly abysmal.

Like others said don't waste money on any other changes before correcting this.

One of the very best and very reasonable too is Carl at Rifle Accuracy Systems Inc Custom Accurate Rifles Barrel Conversions Ruger Mini Remington 700 7400 750 AR10 AR15

Accurizing or building sub moa even sub 1/2 moa AR's is his bread and butter.

 

[Fitch]

Yes, the crown definitely needs to be redone. I'm not sure it will make the rifle shoot as accurately as you might like, but it definitely won't hurt. Accuracy, or the lack there of, especially as the groups get smaller, is the result of the interaction of a lot of variables. The muzzle crown is just one of them. The rifle might still be a dissapointment with a perfect crown if the rest of it is of similar quality to the crown, but it might shoot considerably better if the rest of it is in better shape than one might expect looking at the crown.

My Savage LRPV had this defect in the crown - it got dinged somehow:

It opened the groups up to over an inch. I recut it to look like this:

Groups went right back to where they were.

I'd suggest you take it to a smith and have it recut with at least 1/16" taken off the muzzle. JE's suggestion is a good one.

If it was mine, I'd stick it through the headstock, line it up, and recut it. I don't know how much gunsmiths charge for that, but that's what I'd recommend. I don't know if the rest of the rifle is worth a new barrel or not.

Fitch

 

[loosesniper2000]

Did they use a hammer and chisel on that? Wow, I think they should have paid you to take the gun

 

[gunner69]

I realize this is an older post but some people including myself search older posts for answers.

I never really understood why you would use a bore guide on the chamber end but not on the muzzle crown end. A jag and rod will drag and strike the muzzle crown area hundreds if not thousands of times cleaning during the life of a barrel. I created a simple bore guide for the muzzle crown end and it works really well. We have numerous sizes. There are some good videos on the site too which demonstrate the issue and how the Crown Cradle works. Hope this helps and maybe is seen as a solution or least as extra insurance/precaution for the precision marksman.

Home / Crown Cradle - Baby Your Precision Rifle Barrel Crown

 

[rcoody]

I am a do it yourself kind of guy. This would be the perfect one to learn on. You sure aren't going to screw it up any worse. Lots of satisfaction in doing it yourself.

http://www.brownells.com/gunsmith-t...ool-kits/brass-one-caliber-set-prod18282.aspx