I would check with Strong Side or Stretch to see if they changed the size of the gas port. If I remember correctly at one point they were using a smaller port that in combination with the intermediate gas system would give reliable function with soft shooting. If they opened up the port size then that may be contributing to the problem and an adjustable block would help.
Im using a SLR 7 clamp on adjustable block, JP LMOS, TTI buffer spring and Vltor carbine buffer (2.95 oz) and TTI comp. Works great.
In regards to hand guards, like Tigereye Im using an ALG rail and there is plenty of room. I have tried Noveske NSR and BCM KMR rails and while some people have had luck in terms of clearance its too close for my comfort. On a different rifle I have a SLR clamp on and a SLR ION 15" Ultra Lite Keymod Handguard. Plenty of room with this setup as well.
Good luck.