View Full Version : Gas block / handguard question
12-18-2011, 05:07 PM
I'm building a 264LBC with a 16" Blackhole Weaponry barrel with a mid length gas system. I am torn between using a carbine length free float tube versus a rifle length tube...was planning on going with Red X Arms' for the tube due to price. Either way, I am going to use an adjustable gas block. Question is, if I use a low profile gas block and a rifle length tube, will I still be able to get to the gas block for adjustments?
Similarly, if I decided to use a picatinny rail topped gas block for a BUIS, would a mid-length tube stop BEFORE the block, or would it cover it?
12-18-2011, 05:30 PM
I'm running a rifle length carbon fiber tube over a low pro adj gas block. What I did was dremmel out one of the existing ventilation holes in the tube to allow access the adj screw on the gas block. No reason you couldn't do the same with an aluminum FFT.
This is a PRI block and the screw tends to "walk" until the carbon builds up on it so I make note of how many turns out it is (1 1/2) and hit the screw with a dab of white paint for a witness mark.
The carbon fiber is nasty stuff... you do not want to inhale it! I set up a simple jig with my shop vac to evacuate the dust while I was working on it.
12-18-2011, 06:51 PM
On a midlength barrel, a carbine handguard shouldn't be considered, as it would stop ~2" short of the gas block.
A midlength handguard would stop right at the gas block seat, so the gas block would still be exposed.
A rifle length handguard will cover a midlength gas block. Whether there's access to an adjustable gas block will depend upon which gas block and handguard are used.
I don't use a suppressor, so I usually get an adjustable gas block set early on, then never mess with it again. Thus, even if it's inconvenient to remove a handguard for adjustment, after one range trip the process is done anyway.
Make sure to use appropriate components regarding bolt carrier, buffer, buffer spring, etc, and set the system so that it functions reliably with the lightest bullets and fastest powders that you intend to use.
For what it's worth, the BHW 18" midlength 264 LBC barrel that I used for a build had an appropriately sized gas port (~0.081"), and the rifle was not excessively overgassed with a standard (non-adjustable) gas block, at least not to the point that a slight tweak with BCG and buffer weight couldn't fix.
12-18-2011, 11:18 PM
Tailgate I have a mid length with a JP low profile adjustable gas block under their rifle length handguard. If I had an allen wrench with a ball end it would be easy to sdjust. But being cheap I cut an exsisting allen wrench to fit between the block and handguard. Generally once you get it set it doesn't need much adjustment.
12-19-2011, 11:57 AM
If your barrel is .750 at the gas block, another option would be the Syrac Ordnance Low Pro (http://www.syracordnance.com/), which adjusts from the front. Comes with two long hex wrenches to reach, and has a locking mechanism on the adjustment screw. I put one on my 5.56 and like it quite a bit.
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