Cutting Down Standard FSB to work under LaRue HGs?

AR-15 » Rifles, Uppers, Lowers, Barrels, and more

AR Sponsor:

Site Notices

2024's Favorite CCW? | PSA Micro Dagger

[ARCHIVED THREAD] - Cutting Down Standard FSB to work under LaRue HGs?

Posted: 1/12/2006 1:10:02 PM EDT

Has anyone ever cut down and dremeled a standard FSB to use as a low-profile gas block under a LaRue handguard? It looks like it could be done if it was chopped for height and then trimmed for width at the top and the bottom to remove the bayonet lug and sling swivel.

Anybody actually try this?

Posted: 1/12/2006 1:10:51 PM EDT

[#1]

It also has to be profiled like a LaRue gas block, because the rear opening on the tube is shaped almost exactly like their gas block.

Posted: 1/12/2006 1:16:08 PM EDT

[#2]

Why not just buy the right part?

Posted: 1/12/2006 1:22:21 PM EDT

[#3]

It seems worthy of a try if I am not going to use the FSB once I take it off and it could save the $70 in buying a gas block that I will never see. I realize there is very little clearance under the HG, so it would certainly require removing any unnecessary metal on the FSB, especially near the top where the FSB is too wide.

Posted: 1/12/2006 2:01:52 PM EDT

[#4]

Quoted:
It seems worthy of a try if I am not going to use the FSB once I take it off and it could save the $70 in buying a gas block that I will never see. I realize there is very little clearance under the HG, so it would certainly require removing any unnecessary metal on the FSB, especially near the top where the FSB is too wide.

The top will be too wide, the bottom will be too wide, the sides will be too wide..............................you'll be removing alot of metal to do this.

Posted: 1/12/2006 6:37:15 PM EDT

[#5]

I was thinking about doing this and opted to go with the LaRue gasblock.

The problem with a cut down FSA will be the area around the pins. If you take the metal off the FSA to fit through the LaRue rail there will no longer be enough metal on there to force the taper pins up toward the barrel.

Good thought, but no, it will not work.

OTOH, cut FSA's work great with the Troy MRF.

Corey

PS See my gallery and past threads on the Troy MRF for pics of my shaved FSA.

Posted: 1/12/2006 7:34:54 PM EDT

[#6]

Quoted:
OTOH, cut FSA's work great with the Troy MRF.

I just installed my Samson MRFS-R and I agree that it works well. Just take your time and it won't look like total crap.

Posted: 1/13/2006 4:07:11 AM EDT

[#7]

i cut one down for yhm rail but the larue would be cutting it really close and too close for comfort.

+1 on buying the proper gas block

Posted: 1/13/2006 4:46:16 AM EDT

[#8]

This is one I modified to fit under a Daniel Defense 9.0. It turned out well, but it would be a pain to get it to the dimensions you need to install a LaRue over it. If you have the time and a mill it's possible, but $69 would be well spent on the LaRue GB. I'm not looking at one this very minute but I think you'll have to shorten the taper pins and narrow the taper pin area in the sight too, and those babies are hard.

Posted: 1/13/2006 6:00:25 AM EDT

[#9]

i modified this gas block to fit under a yhm modular. its a beowulf gas block. anythings possible with a dremel and a file.

Posted: 1/16/2006 12:38:24 PM EDT

[#10]

Quoted:
This is one I modified to fit under a Daniel Defense 9.0. It turned out well, but it would be a pain to get it to the dimensions you need to install a LaRue over it. If you have the time and a mill it's possible, but $69 would be well spent on the LaRue GB. I'm not looking at one this very minute but I think you'll have to shorten the taper pins and narrow the taper pin area in the sight too, and those babies are hard.

img.photobucket.com/albums/v378/jtacsupply/LMTContouredGasblock.jpg

Hmmm... How much work would it be to make this work under the DD like you've done? I was thinking about the Bushmaster "Vmatch" shaved front sight under a DD.

Posted: 1/16/2006 1:11:06 PM EDT

[#11]

You can drill and tap the bottom of the FSB for a short 10/32 set screw. Once the base is in place tighten the set screw. Then wick in some loctite green (#290). If you need to take it off later, just hit it with a heat gun for a bit. The set screw costs about 12 cents at the local hardware store. No need for the pins then.

I f you have more time than money, go for it.

lawndart

Posted: 1/16/2006 1:17:46 PM EDT

[#12]

Quoted:
Hmmm... How much work would it be to make this work under the DD like you've done? I was thinking about the Bushmaster "Vmatch" shaved front sight under a DD.

This is kind of what I'm having done, but I'm having the original FSB cut down. My thinking is that the OEM FSB held in place by taper pins is going to be a hell of alot more secure than anything you're going to put in with set screws. Since I'm covering it up with a rail, I won't be able to readily check to see if the set screws are coming loose. With the taper pins I think I gain a little extra security and durability over the long haul.

[ARCHIVED THREAD] - Cutting Down Standard FSB to work under LaRue HGs?

AR-15 » Rifles, Uppers, Lowers, Barrels, and more

AR Sponsor:

Win a FREE Membership!

Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!

You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.

Warning

Confirm Action

About AR15.COM

Stay Connected

Newsletter

Contact Us