AR help

[Jcalder]

Having some issues with an AR. 6.5 Grendel, 20" barrel. PSA upper. 60 rounds thru it. Of the first 20, I had to dig I think 6 out that basically stovepiped. Out of the next 40, which were all shot this afternoon, I had another 2-3 that stovepiped. One thing I have noticed is that the brass is ejecting hard and hitting where the forward assist is. I'm not familiar enough with the operating system to know where to start. Upper is new.

Another issue, which could possibly be me, I'm getting a lot of variation on my impacts. Aiming at bullseye, and sometimes it'll go close and others it won't. I'm new to the platform so I may be sighting a bit different each time.

First group of the day. No scope adjustment.

Next group, made an adjustment.

Shot the upper right hole, made another adjustment and sent 4. Best group of day.

No adjustment, just another 5 shot group, but my impacts moved.

Shot 10, 9 stayed low, one went into a previous group.

Another 10 round group. No adjustments were made. But you can see how the groups impacted differently.

 

[Jcalder]

Ammo shot was Hornady black 123 eldm

 

[EastTNHunter]

Stovepipes and dinged brass is likely gas pressure. Adjustment to gas block required. If not adjustable, the gas block may not be properly drilled or aligned. That ammo is good ammo.

The POI shifts lead me to believe that it is a scope or mounting issue, or even odd pressure on the fore end… or it could be a gas block issue I guess, but that is probably stretching it a little. How do your handguards or rail look? Any looseness or binding?

I'd call PSA and see what they have to say about both. They have pretty good customer service.

 

[Jcalder]

Stovepipes and dinged brass is likely gas pressure. Adjustment to gas block required. If not adjustable, the gas block may not be properly drilled or aligned. That ammo is good ammo.

The POI shifts lead me to believe that it is a scope or mounting issue, or even odd pressure on the fore end… or it could be a gas block issue I guess, but that is probably stretching it a little. How do your handguards or rail look? Any looseness or binding?

I'd call PSA and see what they have to say about both. They have pretty good customer service.

Most likely, I'll change the rings out as I don't much care for the ones I've got. I'm just not a fan of how they mount on the rail. Hand guards look good and aren't loose by feel, but I did have my front rest much further forward than I usually would. This was the first "good" range session I've been able to do where I could just focus on punching paper and not be rushed.

 

[Omega]

The brass issue is normal for an AR, a piece of felt on the deflector will make the dents smaller or non existent. As to POI shifts, check scope mount, see if it improves, but some ARs like certain ammo, try different ones or reload specifically for this AR.

 

[Jcalder]

The brass issue is normal for an AR, a piece of felt on the deflector will make the dents smaller or non existent. As to POI shifts, check scope mount, see if it improves, but some ARs like certain ammo, try different ones or reload specifically for this AR.

I'll try to change out the mount this week. I also plan on reloading for this gun, so hopefully things improve. The brass isn't really getting dented, but when one hangs up it's chewing the case mouths up pretty good.

 

[Omega]

I'll try to change out the mount this week. I also plan on reloading for this gun, so hopefully things improve. The brass isn't really getting dented, but when one hangs up it's chewing the case mouths up pretty good. View attachment 128715

Yea, that looks like it's hitting the lugs or feed ramp. What mags are you using? Have you made sure the ramp is well aligned, and they are matched either M4 or rifle. Here is a pic of mismatched barrel extension/receiver, which the Mfr should fix.

 

[Jcalder]

Yea, that looks like it's hitting the lugs or feed ramp. What mags are you using? Have you made sure the ramp is well aligned, and they are matched either M4 or rifle. Here is a pic of mismatched barrel extension/receiver, which the Mfr should fix.

I will check back when I have time to examine it properly

 

[backyardtndeer]

Think I would give psa call and see what they say. It should run without issues with factory ammo.

I run mostly aero one piece or Burris mounts, don't have any issues with either.

 

[Jcalder]

Think I would give psa call and see what they say. It should run without issues with factory ammo.

I run mostly aero one piece or Burris mounts, don't have any issues with either.

I went to order an aero mount and they were out of stock at the time. The mount is a warne, but I don't like how it bolts on. I looked at the Burris, it's a nice mount, but just looks bulky. I may go that route anyway. I'll give psa a call and go from there.

 

[backyardtndeer]

The Burris are a bit heavier. I bought my last aero mount on eBay, was $70 shipped for a standard 1 inch tube mount. May check there, I saw a few 30mm standard mounts.

 

[DC219]

I can't tell from the pic you posted, but if the front scope mount is on the battle rail and not the receiver, that could cause a lot of variation in your groups.

 

[Jcalder]

I can't tell from the pic you posted, but if the front scope mount is on the battle rail and not the receiver, that could cause a lot of variation in your groups.

I made sure to stay on the receiver. I figured if I didn't it would do like it is.

 

[DaveTN]

Sounds to me like you have two issues, a feeding issue and a POI issue. I'd deal with the feeding issue first. 6 out of 20 is a problem. Can you describe what the failure is? A "stovepipe" should be pretty easy to clear. But you say you have to "dig" it out. The case damage in the center isn't normal. Did you do that damage getting it out?

When the gun does feed a round, does it always go into battery and fire? Or are you having failures to fire a chambered round also?

 

[Jcalder]

Sounds to me like you have two issues, a feeding issue and a POI issue. I'd deal with the feeding issue first. 6 out of 20 is a problem. Can you describe what the failure is? A "stovepipe" should be pretty easy to clear. But you say you have to "dig" it out. The case damage in the center isn't normal. Did you do that damage getting it out?

When the gun does feed a round, does it always go into battery and fire? Or are you having failures to fire a chambered round also?

No failure to fires. I guess my "digging" out is laziness to drop the mag and rack the action, I usually try to pull the charge handle and turn the gun to side so it'll fall out. The worst is when my empty gets hung up and it's trying to feed the next round. Dropping the mag and clearing is sufficient to clear it tho. I didn't damage any of the cases. That's how they came out. If I didn't reload, or brass was readily available I wouldn't mind as much, but at the moment it's kinda hard to get or just plain expensive. Gun feeds fine, fires fine. Just doesn't like to eject properly

 

[Jcalder]

Yea, that looks like it's hitting the lugs or feed ramp. What mags are you using? Have you made sure the ramp is well aligned, and they are matched either M4 or rifle. Here is a pic of mismatched barrel extension/receiver, which the Mfr should fix.

I still haven't had time to check the lugs and examine, but the mag is a c-products 10 round magazine

 

[DaveB]

Stovepiping issue is interesting. I'm thinking it has to be something wrong with the pressure because the case mouth damage says(to me) I am not getting enough gas to fully eject the brass and am slamming the un-ejected case back into the lugs.

As for the POI I have positive good leftover glass that I will swap on to a rifle that has floaters in a group.

 

[nso123]

I am going with a gas issue as well for the feeding issue. As for the shifting POI, if the scope and mount are good you could be getting ready to go down the rabbit hole of accurate gas gun building. That can be fun stuff.

 

[Omega]

I hesitate to say gas as most ARs are over gassed, but many like to run wet, so if the BCG isn't lubed well it may be giving too much resistance.

 

[Jcalder]

I hesitate to say gas as most ARs are over gassed, but many like to run wet, so if the BCG isn't lubed well it may be giving too much resistance.

Being new to gas guns, direct me on lubing the bcg properly.