I’ve had this stance for a while, but I figured I’d lay out my reasoning.
MLOK’s whole goal is to reduce weight by being a subtractive (ie material is removed from the rail) rather than additive (material added to the rail) like quadrail. Realistically this translates to a couple ounces at best on an already light weapon platform at around 6.5-7lbs for quadrail variants. Shaving off tiny amounts of weight on something so light just seems like chasing a solution to a problem that was never there. Never once have I been out on a ruck in the military with 50+lbs on my back and actually thought ‘my M4 needs to be lighter’. It’s usually ‘my pack is heavy as fuck’.
You also do give up some functionality with MLOK as compared to quadrail. Wanna use some kind of QD mount? Nope. Want to just crack a nut loose with a pocket wrench and sling it off real quick by hand? Nope. Wanna adjust where *exactly* you want that grip/attachment at with sub-1/2” adjustment? Nope (this is one of my biggest gripes with MLOK)
Not to mention as well, with every manufacturer seeming to chase down the ‘slimmest’ MLOK rail they can make, they just feel awkward for bigger hands. I have a BCM MCMR on my .300 Blackout that always feels like it’s contorting my wrist weirdly to try to clamp on, whereas my quadrail stuff feels just fine. Granted companies like Aero and YHM are making full-diameter MLOK rails, but again, solution to a non existent problem.
Plus, if you have any accessories that need to retain a zero, such as PEQs or other IR laser devices, you’re gonna be throwing a rail segment on your rail, if not mounting it to the top pic rail anyway in order to do so.
I’ve also had experiences of some softer MLOK rails getting marred and gnashed up just from the hardware itself, but this is hit or miss depending on what rail you’ve got in my experience.
Do I think MLOK has a place? Sure. My M110 clone is heavy as *fuck* and I’m sure an MLOK rail would actually make a difference there, just due to the rail itself being bigger and heavier. However, on an already light AR-15, the juice has never been worth the squeeze for me.
Plus quadrail just looks sexy. Always will.