What mounting system is this?

[BlueGecko]

I found this mid length magpul forearm and don't recognize the mounting system.

 

[coastalnc]

I "think" it's their proprietary MOE mounting system. But don't quote me on that.

 

[Button Pusher]

M-LOK or MOE

 

[Trevillian]

That's the old "moe" system before Magpul created the "standardized" mlok about 10 years ago.

Used to (still do?) make MOE accessories that have tabs that reference off the slot with oval shaped washers with an offset screw hole to attach it.

I still have a few old style. Didn't need to upgrade. It's been a while but if I remember right, it just took a few swipes with a file to flatten/thin moe slots on Magpul plastic to get mlok to fit well.

 

[BlueGecko]

It's MOE, I'll have to retrofit my mlok rails. Thanks guys!

 

[DrScaryGuy]

It's MOE, I'll have to retrofit my mlok rails. Thanks guys!

smart choice. it is difficult to find moe accessories. the price of a new handguard isn't so much.
feel free to mail that useless old thing to me though. i have a mid upper coming and i don't intend to keep the carbine-style handguard on it forever