View Full Version : Griffin armament low profile rigid rail and adjustable gas block question

17 December 2016, 07:31
I'm looking at griffin armament's rigid low profile m-lok rail for an upper I am building. Although for the life of me, I cannot find where I read it, I read last week sometime that the primo gas block that comes with the rail is reccomended for clearance issues. It also went on to say other blocks may work, but fitment is not guaranteed. If I use the barrel I am intending to use, 16" carbine length 5.56, I would really like to run an adjustable block. Does anyone have this rail with an adjustable block that they know works? In photos, the primo block LOOKS like most any other low profile block, but without a measurement or a real world answer, I don't trust a photo.

Edit--- unable to delete the post, but I found a buyer for the barrel. So this may be a moot point now. However I still plan to go with this rail system, so if anyone knows the answer, it wouldn't hurt to know still.

17 December 2016, 10:03
I don't know about these specific Griffin products that you're talking about but way back a couple years ago a flaw was experienced from the M-Lok system. At the end of the day like it or not it falls on Magpul. I imagine what they are saying is similar to what I had with my SLR rail.

Whatever gas block you use and whatever barrel you use, the gas block will fit on the barrel. It will function fine. Also generally speaking if it's low profile enough it will fit under the rail.

Where the problem arises is when you try to put M-Lok accessories up in the area around the gas block. The T-nuts that secure the accessory don't have clearance. The screws will protrude and make contact with the gas block and the T-nuts won't be able to turn into place.

I don't have any idea how Griffin solved the problem but SLR made the OAL of their gas blocks shorter by quite a bit. The shortening (front to back) of the block made it so the screws could go in and the T-nuts could turn and lock into place without any interference.

That is the only thing that could possibly be what they are referring to. With a regular old gas block and a slim rail any M-Lok accessory can't be put anywhere near the gas block. So basically to accommodate for that a few manufacturers started altering the dimensions of their gas blocks.

17 December 2016, 14:13
The rail is similar to SMOS version. A superlative and SLR adj blocks fit fine. I had a superlative under mine. I'm selling my 10.5 Griffin rail if you are interested. And the gas block. And an 11.30 Wilson barrel that mates perfectly with it.