which gas block?
I have an LMT 14.5" upper with M203 bbl profile and standard FSB. I want to install the 13" VTAC Battle Rail to it and I dont know what low profile gas block I need.
Should I use SKU# VLGB-1S-B, or SKU# VLGB-1C-B?
You'll need the .750 diameter - so it would be the VLGB-2S-B or VLGB-2C-B. We have used the clamp ons and knock ons (set screw) - both with good results. Clamp on will be easier to install and the set-screw model may take a little tap to get it on. Just use thread locker and either will serve you well.