I was asked to troubleshoot a 300 Blackout AR build that was not cycling. The gas block is a set screw type and is set back from the barrel shoulder the width of the handguard retainer. This is causing about 1/3 of the gas port to be covered. I took off the retainer, set the gas block against the barrel shoulder and now the rifle runs great.
I'd rather keep the handguards as is so I need a rail height gas block that is compatible with a standard front handguard retainer. Any suggestions ?