At the moment I think a combination of a coiled spring pin (not to be confused with a split roll pin) and set screws would be more than adequate for securing low profile gas blocks – particularly ones that are mounted beneath rails.
What is the current consensus on the best methods for securing low profile gas blocks? I read this very informative thread about gas block pinning but it is pretty old. Is there a problem with the spring pin/set screw method I described?
That appears to be the technique AAC uses to secure gas blocks on their 300 blackout guns.
IIRC, Geissele ships their gas block with a coiled / spring roll pin. It is certainly easier, since you don’t have to ream it for a tapered pin. Everything I’ve read has indicated that it’s completely acceptable, even if it isn’t en vogue.
I think either a spring or regular roll pin would be OK. Spring pin is perhaps better for maintaining alignment during driving in than a roll pin (more compliant)…
Either way, you should use a flat punch or better yet a roll pin punch to drive it in. Brownells has punch sets… A flat pin punch will work… Don’t use a phillips screw driver (as seen on a YT video…ouch)…
Get the hole started well (i.e. in a vice on a drill press at the right angle), keep a good feel for the drills movement and cut (use plenty of lube…WD40 or such). Drill a starter hole a few drill sizes smaller than finish cut, then final cleaning cut at correct diameter. Deburr holes on both side with a larger drill or countersink (to aid in starting roll/spring pin insertion). Blue with cold blue if you have some (Oxpho blue or equiv.).
The taper pins, when properly installed, can be like a wedge to lock the gas block up tighter. Probably the best answer for a cheaply produced FSB and still not even a requirement.
I’d think a “fancy” quality made gas block would benefit even less from that, between no leverage on it and the set screws providing pressure.
Honestly, you could probably set screw the thing and peen the face over a bit and it’d never move anyways.