Groups opening up with SOCOM 7.62 RC2

[kmc0929]

Groups go from 1/2" to almost 2" when the RC2 is attached. Remington 700 bolt gun with a 18" heavy Hart barrel and a open tine SF flash hider.

Inserted a Geissele concentricity rod and it looks perfect... Anything else that could be causing this? What would be the best way to start trouble shoot, issues occurred with both 168GR Gold Medal Match and 168 Winchester Supreme SMK. Once you remove the can, the groups immediately come back down to 1/2".

 

[sleeplz]

Have someone else shoot it just to make sure.

 

[j-dubya]

Is this your first time shooting it or is it a new problem?

 

[Lazlo]

Groups go from 1/2" to almost 2" when the RC2 is attached. Remington 700 bolt gun with a 18" heavy Hart barrel and a open tine SF flash hider.

Inserted a Geissele concentricity rod and it looks perfect... Anything else that could be causing this? What would be the best way to start trouble shoot, issues occurred with both 168GR Gold Medal Match and 168 Winchester Supreme SMK. Once you remove the can, the groups immediately come back down to 1/2".

I had this same issue with a Surefire 762 suppressor purchased in 2008 (forget the model number). Groups would open up once the barrel got hot. I could shoot <1moa for the first 6 shots, and then it would repeatably go low-left up to 6" @ 100yds. I'm no expert shot, but I can maintain a damn <6" group.

Barrel was a Hart 7.62 18.5" 1/10 with open SF flash hider, coincidentally.

Groups would go back to center once the suppressor was removed, and I couldn't detect any concentricity changes by looking down the barrel. I put together a little .ppt presentation, and found a technical contact at SF through their CS dept. They suggested I send it back, and after little chat with the ATF on how to do this legally, I got it back about a month later repaired.

I emailed the tech contact asking - as nicely as I could - what the hell they fixed, and never got an answer. It's fixed in any case... pretty sure I'm going to go shoot it tomorrow.

Feel free to PM me if you want to run this down in greater detail.

Edit: You'll probably get a better set of responses if you post this in the suppressor section.

 

[Gasgun]

Send it back to SureFire.
Their customer service is excellent in my experience.
My 762RC gives me a consistent <1 MOA POI shift and no reduction in accuracy.

 

[nn8734]

Could be slightly differing barrel harmonics with the can on knocking the rifle out of its “accuracy node”. My AXMC (6.5 CM barrel) has appx 1/2” larger groups with the can off. This is with my hand loads. I developed those loads with the can on. POI shift is also dramatic - 2.5” at 6 o’clock on vs off...my can is a 30 cal SAS Arbiter.

Hope you can get it sorted out. I hate shooting unsuppressed...