Quote Originally Posted by sinister View Post
The Griffin XM Linear Comp had a single baffle and is effective giving you back-pressure (for short barrels) and a little flash suppression.

A straight extension serves as a "Viz Mod" (visual modification) but really doesn't do much for you (functionally). They were all the rage in the 80s up to the '94 ban.

If it's not machined true coaxially it can make for larger groups (like a bad crown).
All that. Which is why you don't see XM177 type flash hiders on current 10.3/11.5 SBRs unless you are building a clone. For the same space you could mount a SF mini and get actual suppression.