11.5 upper

[cliffw]

I want to add an 11.5 upper to my collection of AR’s one like Chris Costa shots and every time I go to Bravo Co. they are on back order. I have built several AR’s over the years, but I’m not sure what gas block to use for this one that will fit under the Knight Armament Company URX II. What barrel would you suggest?
Thanks for any and all help.

[Hmac]

Centurion Arms makes good barrels, and they make an 11.5 CHF barrel with the thicker chrome lining that is reputedly very good. I don't know about the URX rails, but I believe a low profile gas block like the VLTOR will fit it. I would consider calling Centurion and ask if their gas block will fit under a URX.

[Iraqgunz]

Have you considered purchasing the upper and the rail separate, then cutting and grinding down the FSB? Then send them off to whomever has a URX wrench and have it installed.

[cliffw]

Hmac, Thanks for the good info.
Iraqqunz, I have a stripped upper and I was thinking if I was going to buy new parts to finish it. If I had and spare FSB lying around I would do that.

[Wicked]

Have you considered purchasing the upper and the rail separate, then cutting and grinding down the FSB?

When I need a low-pro gas block, I order a barrel with a FSB and mill off the sight tower. Call me crazy, but I trust a pinned base. I KNOW it isn't moving. It helps that I've got the right machining equipment but it could be done (and still look nice) using simple hand tools if one works carefully.

[Iraqgunz]

I do the same thing whenever possible as I don't care for screwed on gas blocks.


When I need a low-pro gas block, I order a barrel with a FSB and mill off the sight tower. Call me crazy, but I trust a pinned base. I KNOW it isn't moving. It helps that I've got the right machining equipment but it could be done (and still look nice) using simple hand tools if one works carefully.

[timebandit]

Aim Surplus has a killer deal on the Spikes/KAC URXII 11.5" upper

[TACAV]

Have you considered purchasing the upper and the rail separate, then cutting and grinding down the FSB? Then send them off to whomever has a URX wrench and have it installed.

To the OP,
Robb Jensen on this forum does great FSB shave jobs and I'm 90% he also has a URX wrench. You might want to send him a PM or call him up at Virginia Arms.

[foxjordan22]

Aim Surplus has a killer deal on the Spikes/KAC URXII 11.5" upper

This. I got one and it is a solid upper. Runs great with my A5 system and LMT enhanced BCG.

[cliffw]

Thanks for all the help!

timebandit, Thanks for the info, I order one.

[charmcitycop]

........

[HCL3]

I think Adco will shave down a fixed FSB as well

[timebandit]

Thanks for all the help!

timebandit, Thanks for the info, I order one.

You'll love it. Mine is awesome.

[Pax]

It should be fairly obvious, but nobody's made a point of stating it so I'll just make it perfectly clear: Cutting down a FSB is a great option for a rock solid, low profile gas block. DO NOT just go at the thing with an angle grinder and call it a day, though. I guarantee you the metal in the FSB will prefer a good hand saw and file set. Its like cutting down a shotgun barrel. As a general rule, getting heat-treated components that are subjected to a metric shit-ton of force and heat on a regular basis nice and cherry red is not the best of ideas.

[Hmac]

I had a BCM 11.5 BFH barrel from BCM. I bought a VLTOR low-profile gas block and a DD Lite 9 inch rail online from Rainier and also bought the "install gas block" option. I sent them the barrel, for $25 they pinned the gas block for me. Fortunately, although I forgot to tell them, they also installed the barrel nut for the DD Lite rail before pinning the gas block, so all I had to do when they sent the stuff back to me was install the it on the upper (didn't have to un-pin the gas block to get the nut on). The gas block is thus pinned, as well as held with the two set screws, one of which is in the barrel dimple that BCM does on these barrels.