View Full Version : Low pro gas block question
My 6920 duty rifle is in need of a rail upgrade. The current rail is an ARMS #50MCV. Nothing wrong with the current rail, its solid and has never come loose. However I want a little more rail space and want to mount my light further forward to reduce barrel shadowing. I at leats want a 10", thinking of a DD lite. I will need a low pro gas block to do this but being a duty rifle my department is restrictive as to what I can do to it (shaving a gas block is a big NO NO) With that being said is there a low pro gas block out there that uses the standard pin indexing slots of a stock FSB? I am not allowed to work on my duty rifle, per dept policy only a dept armorer can work on it so sending it out to ADCO is a no go. If I cant come up with a solution I guess I will be left with having them install a 12.0 FSP. Any advice would be greatly apreciated.
I believe that you are going to have to go with the 12.0 FSP or you may want to consider then new(er) one from Troy. I believe that it's a drop in and has a slot for the FSB.
My 6920 duty rifle is in need of a rail upgrade. The current rail is an ARMS #50MCV. Nothing wrong with the current rail, its solid and has never come loose. However I want a little more rail space and want to mount my light further forward to reduce barrel shadowing. I at leats want a 10", thinking of a DD lite. I will need a low pro gas block to do this but being a duty rifle my department is restrictive as to what I can do to it (shaving a gas block is a big NO NO) With that being said is there a low pro gas block out there that uses the standard pin indexing slots of a stock FSB? I am not allowed to work on my duty rifle, per dept policy only a dept armorer can work on it so sending it out to ADCO is a no go. If I cant come up with a solution I guess I will be left with installing a 12.0 FSP. Any advice would be greatly apreciated.
I figured it was unlikely for it to exist. One would think there would be a low pro modelled after a standard FSB since they are so popular for its toughness. Oh well I guess a DD 12.0 FSP is gona have to do for this rig.
Thanks for the advice Iraq
the 9.5 FSP is a nice rail, too. not quite 10", but not as heavy as the 12.0.
FSP rail setups are pretty heavy, relatively speaking.
also.. so you CAN do a low-pro block and run a rail out over it, so long as you don't saw through your FSB? then just use a vltor set-screw gas block.
I ruled it out because I didn't think he would be allowed to remove the FSB and he indicated he wanted a pinned type gas block.
the 9.5 FSP is a nice rail, too. not quite 10", but not as heavy as the 12.0.
FSP rail setups are pretty heavy, relatively speaking.
also.. so you CAN do a low-pro block and run a rail out over it, so long as you don't saw through your FSB? then just use a vltor set-screw gas block.
Iraq is correct, I would feel more comfortable with a pinned block since this is a duty rig and will be getting bumped and banged into things every day. I am starting to consider the 9.5 fsp since its much lighter. I was gona use the 12.0 and put an x300 in front of the FSP. But with a 9.5 I can just go traditional and mount a scout at either 9 or 3 o clock on an off set mount.
I noticed the 9.5 side rails have some holes drilled on the side rails towards the front(on either side of the FSP) will this affect the mounting of a Gear Sector scoutlight mount?
One last question, were can one find the best deal on one of these? I have heard DD offers an LEO discount but is not very significant and they can still be had cheaper through third party vendors.
I just had a crazy thought, how about a Colt flip up front sight gas block ( the ones on the 6940 )? They seem to use a standard M4s pin holes and it would go great with a 9.5 FSP. Ultimately what I wanted to achieve with alonger rail and low pro gas block was to get more rail space and flip up front sights. This seems to do just that and my dept armorers would be able to armore it just like a standard FSP.
Any thoughts?
Belmont31R
04-08-11, 13:58
When FSB's are installed they are held in a jig, and drilled through with the barrel. Its a one-off process where you can't just put on another gas/block and use the same pins.
The closest thing Ive seen done was the new FSB installed over the barrel that already has FSB pin slots, and they used a larger drill with subsequent larger pins. That would rended the old FSB useless, though.
I don't see any issues with running a set screwed in gas block under a rail. The rail will protect the gas block from being hit. You just have to make sure you have a divot in the barrel for the set screw to engage, and use the proper thread locker on the screws.
I would not use a clamp on style gas block. Those are the ones you have to worry about loosening.
Both the 9.5 and 12.0 FSP would require removal of the FSB and then reinstall so you can slip the new barrel nut into place.
WOW, thanks for that tid bit of info on FSBs, did not know that. I will stick to my fixed FSB and go with a 9.5 FSP. My range armorer is able to remove the FSP and barrel so no worries there.
Some what of an off topic question, how much does a standard barrel nut weigh? Trying to figure how much weight I am gona loose or gain going from an 8.6 oz ARMS rail + standard barrel nut to a DD 9.5 with the DD barrel nut.
I generally don't worry about stuff like that, but the DD rail weighs just over 10 oz.
WOW, thanks for that tid bit of info on FSBs, did not know that. I will stick to my fixed FSB and go with a 9.5 FSP. My range armorer is able to remove the FSP and barrel so no worries there.
Some what of an off topic question, how much does a standard barrel nut weigh? Trying to figure how much weight I am gona loose or gain going from an 8.6 oz ARMS rail + standard barrel nut to a DD 9.5 with the DD barrel nut.
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