How often if at all do low profile gas blocks loosen? On the first rifle I built I used a 87industries pin block. I am not sure if I want to pin the gas block on the .300 blackout rifle I am building. This isn't a "battle rifle" or training rifle. Do any of you have a suggestion for c was .750 gas block I should use. It going under the rail so it doesn't have to look like the Fortis gas block. Thanks.