Question for the AR Guys

[Pawnee Bill]

Built a match grade AR15 some years ago before I had a borescope. Drug it out the other day to shoot it again as it never shot like I thought it should considering the high quality barrel (major barrel maker). It still doesn't shoot like it should, so as I was cleaning the barrel I ran the borescope in it and this is what I found. It looks like when they drilled the gas port hole it splintered and tore.

It is pretty obvious this is my problem. Looks like time for a new barrel. Thoughts?

 

[rwj]

Looks like erosion caused by high temperature gases flowing into the gas tube, not uncommon. Doubtful that it’s the source of it not shooting to your expectations.

 

[Danoh]

That's fairly normal erosion (for at least a few hundred rounds). I've seen worse that still shot very well.
I'm with rwj, I'd look at other possible reasons for poor accuracy.

 

[m1jeff]

Mine don’t look that good, and they hammer.

 

[mac86951]

+1 to above, IME a good cleaning is needed when I bring my match rifles out again. I've had same accuracy concerns and a tear-down and reassembly has fixed it for me.

-mac

 

[spclark]

Nope, not tearing. What you’re seeing is typical gas cutting of port. Shouldn’t affect accuracy a bit. My 2007-era 6HAGAR spacegun’s original Kreiger has ~ 3,000 rounds on it, looks worse than that. Still cleans MR-1C if I’m having a good day.

 

[mousegunner]

Ive had three barrels on three guns, 2 Wilsons and a Shilen that all shot better than me. Never looked at the gas port just paid attention to my reloading.

 

[pirate ammo]

I got a SP1 72 year shoots good but I'm not going to say great 1in group at a 100 I'm good..

 

[BOLTED]

Get two different boxes of high quality factory ammo that you think it should shoot well. Shoot some of each box, (not all) and record the results. Before changing anything, I would just tear it down, inspect everything, then put it back together making sure every part mates as it should, and torque each part to spec. Then re-test using the same boxes of ammo. If nothing changed, look for other issues besides the gas port, using the process of elimination. Swap the bolt, swap the carrier, check the chamber with a OAL gauge, double check the twist rate, check the opening on the gas block and tube etc... Swap the barrel if nothing else helps. Sometimes finding the problem can be a pain, but it can also be a very rewarding process. You really get to know a gun when you break it down time and again paying attention to every little detail, trying to nail down a problem. Only change ONE thing at a time, and record the changes.

Extra tip...An old boss taught me to always GET MORE LIGHT! So many things are missed, and or inadequately inspected due to poor lighting, and it has helped me more times than I care to admit. Look for any parts that may be wearing or rubbing where they shouldn't be. Best of luck, you will find the problem.

 

[mikehotel]

Shooting an AR for accuracy may be a little more challenging then you think. When you pull the trigger there are 3 thumps, 1 back, 1 forward, and another back. So trigger discipline is paramount when shooting an AR... hold the trigger back until everything stops moving, just like shooting a pistol. 2. Over gassing; are you using an adjustable gas block and is it adjusted properly, check you tube on how to setup. I'm assuming that you are shooting the proper weight bullet for the twist barrel that you have. A 50 grain v-max is not going to preform in a 1in7 twist barrel, but you know that. Cheap ammo is a no no. If you have a 1in8 twist, your best bet is 69 grain SMK's over 25 grains of varget. And finally, shot off your bench-rest instead of a bipod until you have everything under control. When you are ready for the bipod, get an Altas. ( gunwerks has an excellent video for shooting off a bipod, and demonstrates why you want an Atlas.)

Good luck and have fun.

 

[5spd]

Just about every AR15 barrel Ive bought had had some sort of gas hole shaving, all shoot very well. Some of mine are worse than yours. 1 bbl even had big shavings from the hole drilling all around it like a post hole. None of mine are match grade builds though.

 

[Hino895]

I would think the question is, what are you expecting out of the barrel and what are you getting out of the barrel.

 

[msinc]

Built a match grade AR15 some years ago ........... it never shot like I thought it should........ It still doesn't shoot like it should............Thoughts?

Can you tell us what kind of groups you thought it should shoot at 100 yards???? When you say "match grade", what exactly is "match" about it?? I mean, is it just the barrel, what trigger, etc.??? I know guys that believe just because it's an AR and their buddies told them it will, believe it should be shooting one ragged hole....that's not being realistic. Not saying an AR cant, but most will not. Most bolt guns will not either.
Ar's typically shoot pretty good with decent ammo and a capable shooter pulling the trigger, but I can tell you that simply taking it apart and putting it back together is very extremely likely to NOT result in any great accuracy improvements. It has also been suggested that you replace several parts that don't necessarily enhance accuracy as well...I wouldn't suggest you count on that to do it either. I do not believe the gas port cutting has much to do with the way the rifle shoots accuracy wise.
If it were mine I would look at a new barrel and a good trigger. First though, and don't take this wrong, try shooting one of your buddies AR's that is a known good accurate shooter and see if you get reasonable results like he does. If so, I would go with "throttle up" on a new barrel and {possibly}trigger. If not, I'd let him shoot yours. Again, not trying to say you might be a bad shot, just trying to rule out every variable.

 

[jepp2]

The only time I have improved accuracy of an AR by "taking it apart" was when I corrected an issue. It could be barrel nut torque, gas tube hitting receiver, etc.

I try and follow these recommendations as much as possible: http://bulletin.accurateshooter.com...curate-ar-robert-whitley-explains-what-works/

I have an AR with a Krieger barrel. It shoots about as well as an AR can without being a Whitley. Here is a target at 100m, so it would be ~10% tighter at 100 yards.

 

[Pawnee Bill]

Can you tell us what kind of groups you thought it should shoot at 100 yards???? When you say "match grade", what exactly is "match" about it?? I mean, is it just the barrel, what trigger, etc.??? I know guys that believe just because it's an AR and their buddies told them it will, believe it should be shooting one ragged hole....that's not being realistic. Not saying an AR cant, but most will not. Most bolt guns will not either.
Ar's typically shoot pretty good with decent ammo and a capable shooter pulling the trigger, but I can tell you that simply taking it apart and putting it back together is very extremely likely to NOT result in any great accuracy improvements. It has also been suggested that you replace several parts that don't necessarily enhance accuracy as well...I wouldn't suggest you count on that to do it either. I do not believe the gas port cutting has much to do with the way the rifle shoots accuracy wise.
If it were mine I would look at a new barrel and a good trigger. First though, and don't take this wrong, try shooting one of your buddies AR's that is a known good accurate shooter and see if you get reasonable results like he does. If so, I would go with "throttle up" on a new barrel and {possibly}trigger. If not, I'd let him shoot yours. Again, not trying to say you might be a bad shot, just trying to rule out every variable.

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.

 

[Bc'z]

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.

It sure sounds like it should shoot.
What's your load?

 

[Pawnee Bill]

It sure sounds like it should shoot.
What's your load?

Lapua 223 Match brass, CCI BR4 primers. The best load I had was with a 69 grain SMK with 22.0 grains of H322 at 2818 fps. 10 shot group at 100 yds was .772.

 

[Bc'z]

I've shot Sierra and nosler 69gr bullets and didnt have much luck with them, about the same results your getting.
Also 1n8 twist.
Now 55gr balistic tips and Sierra 60gr HP's
are a different story.
Federal ar match srp w/55gr 25gr benchmark
Cci400 w/60gr hp 25gr benchmark
These wont help for long range but are fun out to 300.

 

[msinc]

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 definitely don't think you are expecting too much sir. 1/2" groups for the rifle you have sounds reasonable to me for sure. Let me ask this, how many rounds have been thru this barrel total??? and, what about copper fouling??? Just wondering if it has had enough rounds thru it to be good and broke in. Some barrels don't take much, some barrels need a couple hundred rounds to shoot their best.
I agree with Bc'z and will say that I too have not had much luck shooting Sierra, most Nosler and many Hornady bullets. I have had very good luck with Berger bullets and either Benchmark or N-140 powder. That said, H322 has also proven to be an excellent powder as well as W748.
I have had so much trouble getting bullets to shoot that I just buy all Bergers. I don't know what is going on with bullet manufacturers these days.
How tight is the upper to the lower receiver??? This has always been, at least in my experience, something that may need addressed. There can be no play between the two, at least not with anything I shoot. Others may get away with slop between the upper and lower, but none of my Ar's ever shot decent until this was addressed somehow. Look at the parting line between the two and wiggle the hand grip while holding the forend tight. If you see or feel any movement at all the rifle will not shoot it's best. I have seen people cob together AR's that slopped around and shot fantastic, but I was never able to get away with it.
Glad you outlived all your buddies...I am 57 and the way I do things you will probably outlive me!!!!!!

 

[butchlambert]

The only time I have improved accuracy of an AR by "taking it apart" was when I corrected an issue. It could be barrel nut torque, gas tube hitting receiver, etc.

I try and follow these recommendations as much as possible: http://bulletin.accurateshooter.com...curate-ar-robert-whitley-explains-what-works/

I have an AR with a Krieger barrel. It shoots about as well as an AR can without being a Whitley. Here is a target at 100m, so it would be ~10% tighter at 100 yards.

View attachment 1099618

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