I would like to know first hand experience with durability of these rails.
I had the mcmr13 on a 16” upper that now belongs to my fiancée. She likes the light weight of her rifle. I really like that rail and how light it is. It seemed to be fine for what I use it for and wouldn’t hesitate to pick up that rifle in a self defense situation. I can’t say I’ve torture tested the thing though, so as far as durability goes, I’m not sure of how durable it is compared to the mk16 and g4m.
I currently have a g4m sitting in a parts bin I plan on putting on a 14.5” build, but am considering going with a mk16. The only thing that’s kind of keeping me from getting the mk16 is that I plan on getting my lower, upper, and handguard cerakoted green all at the same time and I’m not sure if I’m willing to spend the coin for the mk16 just to get it cerakoted a different color, so I might just go with the g4m. I’m still debating it.
I also have a build planned for my dad, and I want to put a lightweight rail on his rifle. The mcmr is the lightest, followed by the g4m, and the mk16 being the heaviest. Now, I’m sure he’ll be riding his quad around with his rifle and I want to put something on it that can handle some drops on different terrain and still hold zero. I don’t want to make the rifle too heavy for him either, so part of me wants to keep the g4m for his build and get the mk16 for my build.
So, does anybody have any experience with all three of these handguards that can attest to their durability and holding zero? How does each handguard anti-rotation device compare to each other?
What I do like about the g4m is the qd mount points built into the handguard. I feel it’s more sleek this way.  The mcmr requires a qd mount to be bolted on, and I might be mistaken, but the mk16 doesn’t look to have a qd mount built into it.

No experience with the MI, but I’ve done the MK16 and the MCMR.  

I think it’s a wash.  The Geissele has obscenely bulky bolt up/attachment nonsense happening around the barrel nut.  They don’t have any lightening holes but the MLOK slots are inline  with each other.  

The BCM has a very well thought out, sleek bolt up and anti-rotate method, and they staggered the MLOK slots.  

Overall the BCM just looks like it was engineered to have cake and eat it too. The MK16 looks like something got lost along the way.  It just doesn’t make any sense.

I only have experience with the Mk16 and I like it so far.  The MI rail seems interesting, though, especially with the titanium nut and clamp screws, which seem like they'd take off at least a couple of ounces.  The dimensions make me think that it is thinner than the Mk16, which makes me wonder about the rigidity of the rail.

The Mk16 does have QD mounts on the 10:30 and 1:30 quadrants at the rear, which are flush with the surface.  The swivels will kind of mar up the area above it with extended use (at least the finish).  If you want to mount QD swivels where MI has its mounts, you'll indeed need to bolt-on mounts (I have an Arisaka mount attached at the 6:00 position all the way forward on my rifle).

Yeah, I like the anti-rotation method bcm came up with. I put their qrf 7 on my colt upper. I also like how tight the tolerance is between their rails and their barrel nut. It’s pretty much a net fit. I had to use a hair dryer to warm it up for it to expand enough for me to install it. I’m pretty sure the mcmr can handle some drops off a quad, Im just unsure of how many drops it’ll be able to handle before it starts bending and the front iron sight ends up losing zero. Not that my dad will drop the rifle from his quad (I’m sure he’ll be super careful with it), I’m just being overly cautious really.

So the mk16 does have qd attachment points built into it. That’s good to know. It seems like the mk16 is the beefier of the 3 choices I listed, so I might end up going that route for my dads build. I can always do a fde color scheme for his rifle so I don’t spend $300 just to have it cerakoted a different color. I can use that money and buy a good barrel for my build.
When I get home this evening I can compare the mcmr to the g4m rail. I’ll post up some pics.

How ‘bout a QRF12”?

Those things are a tube with the rails on it.  Stout asf.

Seems to be lighter than the mk16, but the thing I don’t like about pic rails are the edges. Good suggestion, but I’m pretty set on the mlok rail system.

I have no 1st hand experience with MI handguards but I do most of the other major brands such as DD, Larue, Geissele, BCM and Centurion and I'm in the market for another longer MLOK handguard right now so I was looking (hoping) for a better option.

I have to say, when it comes to MLOK handguards, the MI Combat series is as close as I've found to what I consider the best design. Let me first say, I think any MLOK handguards that don't actual have MLOK slots on all 7 sides is just stupid. Why so many companies only put them on 3 sides is beyond me? Let the end user decide where and how they want to mount their stuff. So taking all the non 7 sided designs off the table...

KAC URX4 - Very close to perfect IMO and some say the way the handguard incorporates the barrel nut makes it the strongest design? Maybe but that also makes installing on an upper with a barrel that has a pinned on gas block close to impossible (and I like pinned gas blocks). Price and availability suck.

Geissele MK16 - Even forgetting the flexibility issues some have reported, for me the biggest issue is the QD Sling Sockets. 1st they aren't even "sockets" really, more like holes drilled in the correct diameter but the real issue is the placement. Unless you use a small 1" sling loop, your sling loop will run into the top rail. I also do not like that they don't have lightening holes under the rail like just about every other option out there. Lastly their massive barrel nut/mounting block is unnecessarily large. Price and availability suck.

Larue LAT - They were just too lazy or unimaginative to invent a new mounting design to give the same continuous top rail look that everyone else has figure out. Just sad.

DD MFR - I was a big fan of DD handguards, Still am if you are wanting a picatinny rail. Their Omega is the best 2 piece design and the DDM4 is the best 1 piece design. The were my go to handguards before MLOK but just can't seem to do MLOK right? The blew it with the MFR. Not crazy about the sling mounts on the MFR (but still better then Geissele) but thing that really kills me is that stupid, pointless angled cut on the front of it. Serves absolutely no purpose except fuck up any plan you may have had to build a no show upper where the end of the rail comes up right to the edge of the threadw so you can mount a can and get that quasi integrated look. I also hate that they are so limited length wise, especially not having a 9.5" version considering they sell one of the most popular 10.3" barrels and their MK18 uppers sell like hot cakes even with the RIS II rail being a heavy ass pig. Oh and the price sucks too for what it is.

BCM MCMR - This one is a good option. My biggest grip is the lack of built in QD sockets.

SLR ION Lite - Another one I seriously considered but their "Anti Rotation" design leaves a lot to be desired.

The MI Combat Rail is the only one I've found that seems to check off all the boxes IMO. Its not as gucci as most of the other brands I mentioned but doesn't cost nearly as much as them either.

Yeah, one thing I don’t like about the mcmr is the lack of a built in qd mount. But not a bad rail and really liked it when I was using it before I gave it to my fiancée.

I did look at the kac urx4, and it looks pretty nice. I didn’t see it in stock anywhere, so I didn’t add it to the list. Now that you mentioned that it’s practically impossible to run a pinned gas block in there, I’ll keep on excluding it from the list. I do like pinned gas blocks as well.

The g4m looks very similar to the mi combat rail, but from what I can see is the mlok positions are all in line on the g4m as opposed to staggered as in the combat rail. Also the g4m has 5 qd mount positions built into it (the 14” version at least). Not sure how I feel about the 6 o’clock one up front. I do like how it looks though and don’t regret purchasing it for one of my builds.

I didn’t like the DD mlok rails. I do plan on getting one of their 14.5” midlength barrels if centurion doesn’t hurry up and put some out.

So far 2 negatives and one positive post for the mk16.

All three are plenty durable, but differ sharply in weight. The MI is likely the lightest of those three, followed by BCM.

The geiselle has a fat nut sack barrel nut mount area that I just dont like.

Midwest Industries is ALWAYS the right answer

I have one that I bought for a 300BLK (no 300BLK ammo so I haven't bothered putting it together yet). I don't plan to sling this one so I didn't care about the QD sockets on this one but it still a strike against it IMO.

I agree but its those 5 QD mounts, especially the one a 6 that kind of kills the g4m for me. I only need the 2 rear ones at 3 and 9 .


So maybe I'm missing something here but why does that matter? I think staggered looks a little better but I don't think it really matters either way?

I consider no QD sockets a plus.  

BCM includes a steel socket with the rail and mounted on either of the top quadrants it’s in a better place than on the side and it stands it off far enough for the sling swivel to clear the top rail.  

Don’t forget Centurion, I have had a couple and all were great

The three QD sockets at the front are the ones I'd be most like to use, especially the one on the left and the one on the bottom.  Saves the need to use full MLOK slots to put mounts in those spots.  I do like the front end of my sling mounted forward, though, and also use the sling as a shooting aid at times.

I have a BCM MCMR 13, MI G3 13 (FDE) and a G Mk16 13 URGI upper.  I had the MI first but wanted a URGI build so eventually , I sold enough parts laying around to get a used one.  I really liked the sleek look of the MCMR and they seem to be used all over the place.  They are all good products.  If I could only have one it would be the MCMR.  It is a solid install and the right balance of weight and size, (OD 1.5"), for a carbine.  The MI is nice but I did not trust the mounting system or like the built in QD. The MI is now on my son's build and has never had any issues.  The Mk16 is slightly larger and heavier with an OD at 1.6 and heavier.  I use a separate QD mount for the sling since a steel QD into an aluminum rail does not make sense to me long term.  The MI Combat looks good but I am railed out of the market now with my numbers of uppers.  For real budget builds you can't beat the UTG Pro SS MLOK.  I have 2 and they are great at their price point.

The thing that drives me away from the centurion c4 mlok rails is that they only have 3rows of mlok. I really do want one of their barrels though.

Here’s some pics of the mcmr and g4m rail. They look pretty similar. I think I’m going to end up liking this rail for my build.

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Of those three, the BCM would be my choice. BCM put more ingenuity into their design and has the locking bolts at the top instead of the bottom; I like this design better because the rail is contiguously tightened around the nut vs types that clamp at the bottom. I think its a more elegant design and holds zero about as well as any clamp on style rail could.

This is the only con to the BCM rails.  They can be a purple motherfucker to get on or off.