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Penn
03-02-2015, 18:32
What does a 5.5" Flash Hinder do for a SBR, other than increase the 11.5" barrel length to 17".

http://www.brownells.com/rifle-parts/barrel-parts/rifle-barrels/ar-15-11-5-w-5-5-fh-5-56-barrel-no-chrome-1-9-sku231000362-69830-142882.aspx?&cm_mmc=external%20partners-_-Second%20Media-_-banner-_-DPMS_barrel

JJ_BPK
03-02-2015, 18:54
Penn

That looks similar to the XM-177 of Nam days. It could be for someone building a retro M16?

I carried one,, it was gently use,, so used it was a smooth bore.. :D

Penn
03-02-2015, 19:07
JJ, understood, but is there an advantage of sound reduction, or any other result related to lengthening a flash hinder, other than accuracy with a longer barrel?

JJ_BPK
03-02-2015, 19:11
JJ, understood, but is there an advantage of sound reduction, or any other result related to lengthening a flash hinder, other than accuracy with a longer barrel?

That is a question I've had for years. It was just a chunk of steel with a bird cage cut on the last inch. Added 6-9 oz?? I know some guys had it taken off and a 1 inch bird cage put on.

The Reaper
03-02-2015, 19:18
JJ, understood, but is there an advantage of sound reduction, or any other result related to lengthening a flash hinder, other than accuracy with a longer barrel?

The sound moderator was first used on the XM177, and it contained internal baffles.

It increased dwell time on the 11.5" barrel to improve reliability, and reduced muzzle blast somewhat.

It is a sound suppressor nonetheless, so it is considered a silencer on a short-barreled automatic rifle.

The current ones out of Brownells are just for looks and don't do anything, to include accuracy, sound, etc., except to make the 11.5" barrel long enough, when permanently attached, to avoid creating a Short Barreled Rifle, which is a Class III weapon required to be on the NFA.

If you were to put an 11.5" barreled upper without a permanently affixed muzzle device of at least enough length to obtain an overall length of 16" or more on a stocked lower, you would be in violation of the NFA and subject to a penalty of ten years confinement and up to a $250,000 fine.

Hope that helps.

TR

Penn
03-02-2015, 19:38
TR, Thank you, your answer directly addressed what I was interested in knowing.

Combat Diver
03-03-2015, 04:29
The 5.5" FH going on a 11.5" bbl would make it legal at 16". There is a .5 overlap for the FH threading on. I used to have one on my first AR build back in 87' to give it that XM177 look. After installing ensure that it's pinned and welded on to keep ATF off your back.

CD