I have used three Syrac gas blocks and one is on a 11.5 inch barrel with a suppressor and have had zero problems with it. But I am stumped why the gas block would be the cause of the different points of impact or gas pressure problems unless your having a problem with the way you mounted it and it is some how shifting with the extra weight of the suppressor. If the internals were gunking up or the adjustable screw was broke you should see the same problem with the suppressor off. Let us know what you find out if you would please. I had problems with the JP adjustable gas block when the adjust. screw came loose during a multi gun match and my rifle stopped cycling. Murphy's curse must be toying with both of us.
I was wondering if the adjustment screw feels any different when you first put it on ? If the adjustment spring and stop pin is broke perhaps the extra pressure from the suppressor is opening the gas port and cycling different.
I was wondering if the adjustment screw feels any different when you first put it on ? If the adjustment spring and stop pin is broke perhaps the extra pressure from the suppressor is opening the gas port and cycling different.