Would you contact the manufacturer Update: Post 24 - Muzzle device issue? Help please

**Steve-0-** · 07-23-16, 16:03

Every manufacturer has the potential to have a bad barrel every so often. For us, our SOP is to get the upper back, re-assemble and shoot 10 shot groups, then assess the results. If it shoots horribly, we replace the barrel.

One thing to note. I the barrel melonite? in rare occasions the process can cause excess corrosion at the crown and cause poor accuracy.

**T2C** · 07-23-16, 16:07

I would definitely contact the manufacturer and ask what is their accuracy standard with your barrel and what ammunition will shoot to that standard.

**Eurodriver** · 07-23-16, 16:52

Originally Posted by Steve-0-

Every manufacturer has the potential to have a bad barrel every so often. For us, our SOP is to get the upper back, re-assemble and shoot 10 shot groups, then assess the results. If it shoots horribly, we replace the barrel.

One thing to note. I the barrel melonite? in rare occasions the process can cause excess corrosion at the crown and cause poor accuracy.

It's a milspec chrome lined barrel.

The upper is already in the mail back to the manufacturer. They did say that my muzzle device torque of 20ft lbs was "WAY too much", but they were very willing to take a look at it and while it isn't repaired yet I have been pleased with the process.

I guess this thread can be put to rest until a resolution is reached.

FYI - that is very good to hear about that policy at SIONICS. It's gotta be tough when a dude writes you an email and is like hey, my upper doesn't shoot. How do you know the guy isn't using sub-par ammo, can't shoot, doesn't have a messed up optic, etc.

**Eurodriver** · 07-24-16, 11:55

Uh oh.

So... I took the muzzle device off the upper that was the subject of this thread and put it on a 10.5" LMT. Again, torqued to 20ft lbs. It is an AAC 51T Flash hider.

It shoots terrible now.

Unfortunately I couldn't remove the muzzle device at the range, but all of the groups with both the NF and a 4x ACOG were similar. It is not the optic, because I was shooting a 4" gong at 600 yards with the 14x Night Force immediately prior to this.

This has been going on for 3 weeks. I can't keep going to the range every weekend trying to diagnose this garbage.

Before anyone asks, yes I know how to use a torque wrench and yes I am, in fact, torquing to 20ft lbs. As a matter of fact, I just removed the muzzle device and despite it being rockset in place it took a gentle "nudge" from a crecent wrench and broke free. It had less torque on it than the A2 with the crush washer I took off a few days ago.

Possible bad muzzle device? I can't see how torquing to 20ft lbs would damage the barrel, because my previous upper shot poorly with it removed as well.

The group in green is from a bone stock 14.5" BCM with a pinned BCM Comp and an umagnified T1.

The group to the right of that in red is a suppressed 10.5" LMT with a Nightforce 14x and SSA-E Trigger.

Ammo is Gold Dots 64gr. The LMT's group is easily twice as large as the BCM's group despite having 14x optic and a target trigger. How on earth?

Has anyone ever seen a perfect circle group like that before? Weirdest thing.

**P2000** · 07-24-16, 13:47

Never mind

**lysander** · 07-24-16, 16:55

Originally Posted by Eurodriver

Uh oh.

Has anyone ever seen a perfect circle group like that before? Weirdest thing.

Every single three shot group I have ever shot have had all the holes make a perfect circle . . .

**mtdawg169** · 07-24-16, 17:12

Originally Posted by Eurodriver

Uh oh.

So... I took the muzzle device off the upper that was the subject of this thread and put it on a 10.5" LMT. Again, torqued to 20ft lbs. It is an AAC 51T Flash hider.

It shoots terrible now.

Unfortunately I couldn't remove the muzzle device at the range, but all of the groups with both the NF and a 4x ACOG were similar. It is not the optic, because I was shooting a 4" gong at 600 yards with the 14x Night Force immediately prior to this.

This has been going on for 3 weeks. I can't keep going to the range every weekend trying to diagnose this garbage.

Before anyone asks, yes I know how to use a torque wrench and yes I am, in fact, torquing to 20ft lbs. As a matter of fact, I just removed the muzzle device and despite it being rockset in place it took a gentle "nudge" from a crecent wrench and broke free. It had less torque on it than the A2 with the crush washer I took off a few days ago.

Possible bad muzzle device? I can't see how torquing to 20ft lbs would damage the barrel, because my previous upper shot poorly with it removed as well.

The group in green is from a bone stock 14.5" BCM with a pinned BCM Comp and an umagnified T1.

The group to the right of that in red is a suppressed 10.5" LMT with a Nightforce 14x and SSA-E Trigger.

Ammo is Gold Dots 64gr. The LMT's group is easily twice as large as the BCM's group despite having 14x optic and a target trigger. How on earth?

Has anyone ever seen a perfect circle group like that before? Weirdest thing.

Sounds like a muzzle device issue. How did the LMT shoot before you installed the mount?

**Eurodriver** · 07-24-16, 17:21

Originally Posted by mtdawg169

Sounds like a muzzle device issue. How did the LMT shoot before you installed the mount?

Hard to say. Obviouslynever shot it with a 14x NF and an SSAE, only a quick once-over zero to get the T1 and Irons zeroed. But with the same 64gr GDHP ammo it shot decently. I certainly don't remember thinking it was doing poorly.

Unfortunately all three of these are new uppers so I don't have many thousands of rounds of experience with them. I guess this will certainly teach me to shoot an upper before making modifications in order to better diagnose if its a manufacturing issue or a modification issue.