So I have a keymod upper I’m building, but I also like the Magpul brand VFGs. I tried a rail adapter & the railed version of the MVG but it’s way too thick so…
I got an M-lok MVG & adapted it to keymod:
Started by cutting the nubs off:
Then the holes need to be ovaled for the keymod nuts. I used a RotoZip bit in a Dremel tool. If you want the item to be reversible you need to oval the hole in both directions. The MVG is symmetric so I just ovaled one side of the holes.
Then made a backing plate from 1/8" aluminum. Drilled the 2 holes for the keymod nuts & the center hole for the locking block. All 3 holes then chamferd for the standard flat head 8-32 keymod screws using a countersink bit. The T-nut looking thing is the locking block. It’s threaded 8-32. The big end is 3/8" and .050" thick (keymod spec). The small end diameter isn’t critical. I drilled a 3rd hole into the MVG between the 2 that were there. (5/16", but take your pick). The small end of the T-nut is a press fit into that hole & becomes the locking block. The depth of the small end depends on the item you’re pressing it into. The MVG is about 1/8" thick there. I made the small end of the nut .100" long.
The locking block is loc-tited & holds the backing plate into place.
My new, Magpul keymod MVG (lying oriented backwards…)
That’s awesome, assuming you’ve measured it correctly and it’s proportions are appropriate that the keymod nuts snug it according to spec against that block.
My first thought was that the polymer might not be the best mating fit but then again the BCM rail sections that they ship with the KMRs are polymer, and they’re actually pretty cut-away on the back side mating surface so what do I know.
Kudos for doing this and posting it. I like the VFGs as well (chopped and ground down.) This is something I would be personally nervous to do with my rail.
I’ve kinda been curious to see what tinkerers will come up with (keymod-wise) and the other thread with the keymod considerations obviously indicates that a number of products haven’t been properly executed.
Neat mod. Prior to several companies releasing keymod VFGs I modded a Magpul RVG (had to reduce the diameter of one of the posts). Of course then I had to install it like I was rocking a Troy VTAC Extreme rail and all the dickery that entails.
I can’t see the polymer here being an issue. With the backing plate on one side & keymod rail on the other, there’s (much) more metal sandwiching the polymer at the VFG/rail interface than there is as intended with M-lok. The plate was layed out & drilled freehand. A nice, machined plate on a mill would be best.
I’m going to try one of the BCM angle stubbies at some point. Initially they looked a bit wider than I want, but worth a try.
Great mod, and nice to see you included a recoil lug. The only way this will give you trouble is if the front chamfer of the KeyMod nut isn’t engaging the front chamfer of the slot on the handguard. That’s needed to get the cross compression KeyMod requires for recoil control. Otherwise, you’re still depending on friction to keep the VFG from sliding front and back even if there isn’t enough play for it to come completely loose.
Nice work. From the pics it looks like a solid setup but I’m curious about contact point mate up and how well it holds up to some live fire exercises and rough use.
