AR Sponsor
Posted: 10/5/2008 5:40:39 AM EDT
I had a pic in another thread of a 3-slot FH mounted on a barrel with one slot facing up and next to it an AR10 FH/barrel extension with a similar (the one I had modeled) FH and the slot facing down... I mentioned that I would try it both ways...It seemed to me that having the slot down would kick up dust/dirt/sand...but I suppose the idea was that the other two slots expelling gas mostly upward would push the barrel down on firing...  In any event, someone asked how I would adjust my FH to get my slots aligned like the AR10 FH...(other than cranking the crap out of it!)...  Mine has a solid steel washer between the FH and the barrel (you can just see it)...so to get it 1/6 of a turn more (or 1/6 less), I would take off (or add) .006"...I suppose I could do that with a piece of a peel washer, but I dislike those...and, they're not retro...  So here's what I came up with...Make a new washer out of steel again, but add (or subtract) .006" to it... These're the tables I would use to "time" my FH... 1/2" x 28tpi Flash Hider Threads 1 thread = 1 turn of FH ...................Actual......Used.... 1 thread = .03571" .036" For Three Prong or Six Slot FHs 1/6 thread = .00595" .006" 1/3 thread = .01190" .012" 1/2 thread = .01785" .018" For Eight Slot FHs (with three slots blanked) (this is the A2 "timed" FH) 1/8 thread = .00446" .005" 1/4 thread = .00892" .009" 3/8 thread = .01339" .014" 1/2 thread = .01785" .018" 5/8 thread = .02231" .022" Just for S&G, I included the A2 (8-slot) FH (the one with the blanked off bottom slots)... I could just take that washer off, and sand/grind .006" off it...but it's probably easier (and more precise) to just make a new one... Hope that answers the question...  (And that is enough of Sunday Morning Math...)  |
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