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Posted: 2/1/2011 12:20:14 PM EST
Are there any lights (like the Surefire x300?) that can be mounted right on a railed gas block? This is on a CMMG Piston Carbine. It is on this AR:

I just installed a DD Omega and moved the MBUS back onto the rail and was looking for an option that would allow me to mount a light in front of it.

Thanks
Link Posted: 2/2/2011 5:45:53 AM EST
20 views and no feedback as to weather or not a weapon light will stand up to the heat of being mounted on a gas block?

Maybe I will just swap the MBUS out for some Troys and run a Scout Light in a Gear Sector mount....

I really liked the x200/300 on the top rail though for ambi use...
Link Posted: 2/2/2011 5:57:12 AM EST
Here is an updated picture of the carbine in question:



I just wanted to make sure it was clear that I have changed a few things around from the first picture.

Like I said, I installed a DD rail and moved the MBUS back onto the rail. Now I have this rail section on the top of the gas block. Is this a suitable mounting location for a Surefire X300 or similar?
Link Posted: 2/3/2011 7:10:14 AM EST
I too am interested in mounting a light and/or laser to the bottom of the gas block on my Stag 8, and , I am also concerned that it would so hot as to melt the components in the light.

Is there a mount, rail extension, or, adapter that is designed to insulate from heat? Maybe it could be adapted to work with a light mount?

Anybody have any ideas?
Link Posted: 2/3/2011 9:15:21 AM EST
[Last Edit: 2/3/2011 9:17:10 AM EST by FlinginLead]
Yes heat will be your problem. Those Magpul BUIS have been know to melt on a gas block. Maybe try mounting the light above your thumb on your quad rail forearm. This seems to be where most people like it. You dont have to adjust your grip much to turn it on.

Edit to add.
i think any adapter or riser will put it too high and in your line of sight. I have seen some pistol lights mounted on a rail i think they just go on. but then again I dont own one.
Link Posted: 2/3/2011 10:00:22 AM EST
[Last Edit: 2/3/2011 10:09:48 AM EST by DallasLooterShooter]
Sorry didn't read it was piston. You probably need to get an offset scout mount because you won't be able to find a good way to run the x300 at 1200

Posted Via AR15.Com Mobile
Link Posted: 2/3/2011 10:27:56 AM EST
[Last Edit: 2/3/2011 10:32:26 AM EST by mc_1_2_3]
I have a Stag 8 which has the rail on the bottom of the piston gas block also. That is where I would like to mount a light/laser, right up tight under the barrel. I currently have a Magpul MOE drop-in handguard. It moves to much to attach a laser and expect it to stay anywhere near zeroed. May just have to wait til I get a sturdier hand guard...

Here is an image I found in another thread. Would like to do the same. He said he put 500 rounds through so far with no trouble, but not at a high rate of fire:

Link Posted: 2/3/2011 2:18:52 PM EST
[Last Edit: 2/4/2011 4:39:06 AM EST by DallasLooterShooter]
Don't know if I was drunk or just stupid
Link Posted: 2/3/2011 7:43:08 PM EST
Originally Posted By DallasLooterShooter:
I'd recommend ditching the MBUS on the front and getting a metal flip up sight for the gas block. Then you can run your X300 on the end of the DD rail


I'm trying to picture what your saying, you are suggesting running a metal flip up on the gas block, and an X300 behind that at 12 o'clock. The light would light up the front sight quite nicely I guess.
Link Posted: 2/4/2011 3:42:55 AM EST
[Last Edit: 2/4/2011 3:47:05 AM EST by mc_1_2_3]
Here is a pic of a Lasermax Uni-Max laser that includes a momentary switch with a rail mounting system. The laser mounts to a Picatinny rail AND has a Picatinny rail on the the bottom of it to mount a light.



I emailed LaserMax about the heat capabilities of the laser and mounting it to the gas block. They replied with:

"While doing some testing on heat capability we put a Red Uni Max in
an oven at 350 degrees for 1.5 hours. They forgot it was in there. They
brought it to me on an oven mitt and within a few minutes as the batteries
cooled to operating temperature it began working again. Not a recommended
test.
It, as all lasers are limited somewhat by the batteries they use.
Exceeding the limit won't destroy the laser (within reason) but it will stop
functioning. Upper limit is 140 degrees."

I tried to find some hard numbers on what the gas block temp would be after sustained firiing but it's hard to find. The data that I did find indicated that after firing 80 rounds as quickly as possible, the gas block on a POF P-415 piston AR-15 temp was 320F. Here is the link to that report:

Gas block/Barrel Temp Report

My Stag 8 has the two set screws right on the bottom of the gas block (the block is pinned too). I'm thinking of placing a thin piece of heavy duty insulating material then use longer screws to attach an aluminum Picatinny rail that would normally attach to a handguard. This would leave only the 2 screws to transfer the heat from the gasblock to the laser mount. Then attach a nice low profile light to the rail on the laser.
Should be a safe setup for any light or laser mounted to a gas block.

Link Posted: 2/4/2011 4:42:38 AM EST
Maybe one of those short risers would act as a insulator to some extent. i remember seeing some that were 1 to 1.5 inches long and about 1/2 inch high. But for BobaPunk to mount on top im pretty sure it would get in the way of the optics, BUIS for sure. Might help mc_1_2_3, not as low pro as you like.

Sounds like lasers can take some heat though. Heck try it out can always take it off if you plan on getting it hot at the range.
Link Posted: 2/5/2011 4:50:26 AM EST
The Elzetta mount is secured right to the sight base and it holds up very well.

I doubt it will work for your situation since you have already swapped it out, though.



Don't worry about the heat, I've never heard of one melting, and I've ran it through a couple of carbine courses without issue.
Link Posted: 2/5/2011 3:04:34 PM EST
Originally Posted By mc_1_2_3:
I have a Stag 8 which has the rail on the bottom of the piston gas block also. That is where I would like to mount a light/laser, right up tight under the barrel. I currently have a Magpul MOE drop-in handguard. It moves to much to attach a laser and expect it to stay anywhere near zeroed. May just have to wait til I get a sturdier hand guard...

Here is an image I found in another thread. Would like to do the same. He said he put 500 rounds through so far with no trouble, but not at a high rate of fire:

http://img.photobucket.com/albums/v722/rraaaa/DSC05571.jpg


I have a CMMG LEP II and want to mount an X 300 in the exact same place.

Link Posted: 3/15/2011 7:28:47 AM EST
[Last Edit: 3/15/2011 7:31:20 AM EST by mc_1_2_3]
Sorry it took so long to reply, but, I went with a Streamlight TLR2s, weapon light with red laser. I first mounted a Burris 1/2" Picatinny riser, Burris part number 410340 to the gas block. It is almost exactly the same length as the gas block rail and looks great. This allowed the light to clear my MOE handgaurd, and, provide some insulation from the heat.
With the vertical grip where I have it (and like it) it is very easy to acuate the light paddle switch, either the momentary side or the "ON" side.




Should work very well on your setup too.
Link Posted: 3/17/2011 3:41:10 AM EST
[Last Edit: 3/17/2011 3:42:45 AM EST by JeepinSoldier]
mc_1_2_3,

Thanks for the update and the pic. Im still trying to decide if I want to mount an X 300 in that bottom location on the gas block, or modify a Surefire M 500A dedicated weaponlight forend that I had on my gas M4 before I got the piston rifle. I think with removing one of the heatshields inside and a little dremel work I could make it fit.

Torn between easy/simple/light weight of the X 300 and the integrated switches on the 500. I also hesitate to cut on the expensive M 500A.

Did you have to modify the Magull handgard to get it to work with the piston?
Link Posted: 3/17/2011 4:44:20 AM EST
[Last Edit: 3/17/2011 4:50:51 AM EST by mc_1_2_3]
Originally Posted By JeepinSoldier:
mc_1_2_3,

Did you have to modify the Magull handgard to get it to work with the piston?


Yes, I did modify it with a Dremel sanding drum. Just look at the original guard and use it as a guide. Very simple. You could even use a round file, you are just removing some of the plastic, no metal. Here's a pic. Oh, another "modification" I had to do on the MOE. It moved quite a bit with the vertical grip installed, so, a couple strips of Gorilla Duct Tape on each end of both the top and bottom piece right where they contact the rings. Tightened it up significantly and if done carefully you cannot see any of the tape. Hopefully it will not melt on the front! We'll see.

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