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AR15.COM
11/15/2010 5:21:00 PM EDT
Is there enough room under a Larue rail for a .936 barrel with a lo profile gas block? If so which blocks will work.
11/15/2010 6:09:47 PM EDT
[#1]
There's enough room for the barrel, but the gas block will be tricky. The slimmest one I can find online is the DoubleStar Low Profile Gas Block ( for Bull Barrel,  .936)

I can't find any exterior dimensions to confirm.

The gas block needs to fit through a hole with these dimensions (rounded up):



Note the radius on the bottom...I've had to profile a couple different gas blocks to clear this area in particular.
11/15/2010 6:32:16 PM EDT
[#2]
Quoted:
There's enough room for the barrel, but the gas block will be tricky. The slimmest one I can find online is the DoubleStar Low Profile Gas Block ( for Bull Barrel,  .936)

I can't find any exterior dimensions to confirm.

The gas block needs to fit through a hole with these dimensions (rounded up):

http://i2.photobucket.com/albums/y44/mfingar/GasBlockClearance.jpg

Note the radius on the bottom...I've had to profile a couple different gas blocks to clear this area in particular.


So if I did my math correct I would have .032 or just under 1/32" from the barrel to the insides of the rail. That doesn't sound very promising

ETA... I was planning on putting this on a 16" carbine gas 458 SOCOM (reason for the big barrel ) and want a 12" rail. I was originally wanting to put a DD Lite on but got to thinking I might try a Larue I do have 12" Lite now on another gun I could put it on the 458 and pick up a Larue to replace that one Just might have to give it a try. Might even try the Larue on the 458 first never know it might work and the info might help someone else out in the future.

Thanks for the detailed pic and help.
11/15/2010 6:45:23 PM EDT
[#3]
Quoted:
Quoted:
There's enough room for the barrel, but the gas block will be tricky. The slimmest one I can find online is the DoubleStar Low Profile Gas Block ( for Bull Barrel,  .936)

I can't find any exterior dimensions to confirm.

The gas block needs to fit through a hole with these dimensions (rounded up):

http://i2.photobucket.com/albums/y44/mfingar/GasBlockClearance.jpg

Note the radius on the bottom...I've had to profile a couple different gas blocks to clear this area in particular.


So if I did my math correct I would have .032 or just under 1/32" from the barrel to the insides of the rail. That doesn't sound very promising


Only at the collar near the barrel nut, the rail's ID 1s 1.2"...but it doesn't look good for a gas block...unless you run the gas block externally, then you can attach it after the handguard is in place.

11/15/2010 7:01:21 PM EDT
[#4]
Quoted:
Quoted:
Quoted:
There's enough room for the barrel, but the gas block will be tricky. The slimmest one I can find online is the DoubleStar Low Profile Gas Block ( for Bull Barrel,  .936)

I can't find any exterior dimensions to confirm.

The gas block needs to fit through a hole with these dimensions (rounded up):

http://i2.photobucket.com/albums/y44/mfingar/GasBlockClearance.jpg

Note the radius on the bottom...I've had to profile a couple different gas blocks to clear this area in particular.


So if I did my math correct I would have .032 or just under 1/32" from the barrel to the insides of the rail. That doesn't sound very promising


Only at the collar near the barrel nut, the rail's ID 1s 1.2"...but it doesn't look good for a gas block...unless you run the gas block externally, then you can attach it after the handguard is in place.



I type slow

So if the inside of the actual rail is 1.2" I should be ok I just measured my Lite rail and it was right around 1.2" inside and I have been told that I could do what I am wanting to with a Lite rail. So I would basicly be able to install the barrel nut etc.. then slide on the rail but not attach, then slide the gas block in from the muzzle end, then rotate the rail so I could tighten the gas block through the holes in the rail, then tighten the rail down to the upper?
11/15/2010 7:17:56 PM EDT
[#5]
Great idea, but you won't have enough travel to line up holes in the handguard to access the gas block screws. I'm calculating something like 7 degrees maximum rotation once the gas tube is in place. Sorry.

You could always drill holes in the lug spaces in the bottom. (a 10.0" handguard already has 5 holes in the lug spaces)
11/15/2010 7:28:46 PM EDT
[#6]
Quoted:
Great idea, but you won't have enough travel to line up holes in the handguard to access the gas block screws. I'm calculating something like 7 degrees maximum rotation once the gas tube is in place. Sorry.

You could always drill holes in the lug spaces in the bottom. (a 10.0" handguard already has 5 holes in the lug spaces)


Yea you are right I could drill 1 hole close enough to the upper end of the rail and use it to do all the set screws I guess.
11/15/2010 7:45:01 PM EDT
[#7]
There's already one hole near the end...getting the crews in-position and started on their threads would be very challenging, but plausible.

It you do it under the handguard, you would be the first I know of.
11/15/2010 7:54:29 PM EDT
[#8]
Quoted:
There's already one hole near the end...getting the crews in-position and started on their threads would be very challenging, but plausible.

It you do it under the handguard, you would be the first I know of.


  A challenge!

I might have to put some other things on the back burner and go ahead with this. Wife wont be happy

Did you have a pic of the hole in the rail you were refering to.

Again, Many Thanks!!
11/15/2010 7:59:30 PM EDT
[#9]
Sure
What length handguard?
11/15/2010 8:14:54 PM EDT
[#10]
OK,
Out of morbid couriousity, I did what you're considering (but with a .75" barrell).
It was much easier than I thought.

Lining-up the gas block correctly with the dimples was the hardest part.

Access through the bottom holes was very easy.
11/16/2010 4:00:09 AM EDT
[#11]
Quoted:
OK,
Out of morbid couriousity, I did what you're considering (but with a .75" barrell).
It was much easier than I thought.

Lining-up the gas block correctly with the dimples was the hardest part.

Access through the bottom holes was very easy.


Thanks, sounds like I have rail on my list