Machining would also be simplified by comparison to keymod for aluminum handguards as well. Of course that's only an issue for polymer handguards.

Keymod requires a chamfer for the slots, which you probably couldn't manage with polymer. Might be tough to gain adoption from third party vendors. Never the less, seems like just about all the big name manufacturers are on the keymod bandwagon. I have not gone to war with the rifle but they have not failed me in any way yet. I have polymer keymod rail segments from strike industries and they work just fine. Personally I'd go with the Magpul carbine length handrail.$29.Not sure why Magpul says that keymod does not work well with polymer. The Magpul MLok Handrail is probable the most affordable and reliable handrail on the market From this testing, the M-LOK was selected for use on the Suppressed Upper Receiver Group and Advanced Sniper Rifle program.Looks like to me the MLOK handrail wins! They found that in a drop test, M-LOK accessories remained attached 100% of the time, while KeyMod accessories remained attached only 33% of the time. M-LOK came out on top with the least amount of MOA shift when removing, then reattaching, an accessory rail with a laser sight. The most significant variation was in the Repeatability test. Magpul handrails are the most affordable.In the Endurance and Rough Handling tests, both systems passed. The polymer accessories Magpul offered didn’t work well with the KeyMod’s conical nut. Magpul sought a design that worked better with non-metal mount surfaces.

Just like the KeyMod, the M-LOK allows for direct accessory attachment.

The Modular Loc k, or M-LOK was patented by Magpul Industries and introduced to the market in 2014. This also allows for picatinny rails to be mounted onto the handguard wherever needed. What's a better handrail?Im looking to replace my handrail on my Stag-15 M4 and want either an MLok or Key Mod handrail in a carbine length.I understand the Keymods have all sorts of mounting accessories but not really familiar with the MLOK system yet.The cheapest KeyMods around $50.Instead of having a hand guard with a picatinny rail attached, the KeyMod was designed so that accessories could be mounted directly onto the rail.

Magpul keymod accessories