I've got the exact same SLR GB on 3 rifles, 2 of which are new rifles, and none of which have the SCS. Have never had an issue with either leaking or LRBHO on any of those 3 rifles.
What I'm hearing is that you don't want to believe the folks who have told you the SCS is an issue. The odds of it being a factor are far higher than the odds your gas is block causing the issue.
Also, as has been stated, your gas port size is well below what it needs to be for function's sake.