Newb AR gas block question


Ray P
February 11, 2013, 11:27 PM
For an AR15 with 16" DPMS bull barrel; is there a handguard cap that will work with a .935" D bull barrel at the gas port, and a low profile gas block; or will I need to use a free float handguard?

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Ray P
March 9, 2013, 10:25 PM
When I said "newb", I was referring to my knowledge of ARs and AR builds. Any info regarding gas block and handguard combos for a 16" HB would be appreciated

March 9, 2013, 11:41 PM
If you have a .935" bull barrel, I'm assuming your primary concern is accuracy. To that end, anything but a free-floating hand guard is counter-productive.

Is there a specific reason you are interested in a drop-in handguard?

Ray P
March 10, 2013, 12:44 AM
Actually I put the lower together a year or two back with surplus grip & stock thinking I'd go with a rifle configuration; I never thought I'd use a 16" bull barrel. But I got a very good deal on the barrel recently, and it is time I finished this project. The Sun Devil upper & lower set have been sitting around the house waiting on me for the last 4 years.

I guess I thought the M4 2-piece front end would look best with the A2 buttstock, and I've been having a hard time imagining which free-float tube would work best with which gas block. Some gas blocks seem to go within the forend, some right in front. Some free-float tubes have a screw-in front piece which would line up... where?

I guess I'm just coming to terms with the results of a snap decision.

March 10, 2013, 01:34 AM
There are a lot of limitations with a bull barrel, and there is a reason you don't see a lot of parts available for them. The purpose of a bull barrel is accuracy, at the expense of weight. They are pretty much meant for bench shooting. Seeing that accuracy is their primary purpose, they are pretty much exclusively mated with free floated handguards.

If you go to this link (, you'll see different gas block options that will work with your barrel. The "low profile" gas blocks will fit under any length free floated handguard. The "railed" gas blocks will not. If your barrel is drilled for carbine length gas, you will need a carbine length handguard to be compatible with a railed handguard.

If you're having buyers remorse about the bull barrel, now might be the time to sell it, do some research on what you really want/need, and wait until the right barrel is available.

March 10, 2013, 01:38 AM
If this ( is the "screw in front piece" you are talking about, those are just cosmetic. If you have a gas block outside the handguard, they are installed with the opening at 12 o'clock, to allow the gas tube to pass into the handguard. If a low pro gas block is inside the handguard, it doesn't matter which way they are installed. Again, these pieces are cosmetic anyway, so it doesn't really matter.

Ray P
March 10, 2013, 03:51 AM
Great info & thank-you for the links! No remorse so far :)

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