13" ALG EMRv3 vs BCM MCMR-13 vs Geissele Mk8 rigidity?

AR/M4 AR General Discussion
1

Which one of these is going to be the most rigid? As in, a better host for lasers, iron sights, etc? Which will be the least?

I’m going to replace an ALG EMRv2 since I prefer more top rail, and I have a BCM MCMR-13 inbound and a Geissele Mk8 on the shelf. My go to rifle has an ALG EMRv3, but I’m not tied to any one set up. They all seem to end up pretty close once I throw a RDS on them.

RDS or not, I often turn it off and practice with irons. That coupled with the fact I’d like a night vision setup at some point has me curious about rigidity, maintaining zero, etc.

2

I have very little experience with the ALG rails, but own the MCMR-13 and several variations of Geissele rails including the Mk8. I’d have to go with the Mk8 in rigidity if worried about deflection using IR. The Mk8 isn’t the most ergonomic rail though, I’d look at the Mk14 to be honest or try to find a Hodge Wedgelock or wait for the P-lok to be released.

3

I have no experience with the MCMR but owned a bunch of KMR’s. I currently own an ALG EMR V2 and the MK8.

The MK8 barrel nut is a beast and the rail is bomb proof. Hands down the strongest of the bunch. The ALG barrel nut is pretty robust as well and I use that rifle for PCC, so its gets banged around a lot and my irons have never lost zero. Out of all 3 the BCM has the most flex (i.e. if trying to push rail towards barrel) but it’s never failed so I can’t really hate on it.

4

I have a BCM KMR on one of my carbines and my wife has the ALG EMR-V2. I installed both. The barrel nut on the ALG feel much more robust and sturdy than the KMR. The ALG rail itself is more rigid and seems to handle bumps better regarding flex. Woth that said my KMR is an original, not the Alpha model.

5

I’ve been thinking about saving the Mk8 for a stout 16" precision barrel. To be honest, ergonomics aren’t always my first consideration. When I come off of a rotation of rifle training using quad rail equipped rifles, smaller handguards almost seem small and some of the very small handguards almost too small. It’s a weird thing. I’ll have to take a look at the Mk14. Who makes the P-Lok?

6

Have you considered a urx4?
Seems to be quite rigid. Can amyone comment on how it fairs compared to mk8 in terms of rigidity?

7

Hodge, it should be released soon. FN is using that design in their newer FN-15’s.

8

I have or have had the following hand guards:
15" G MK4
13" KMR
12" ALG V3
10 3/4" URX4
10 3/4" Hodge Wedgelok

URX is the most rigid of the handguards I’ve used, though the G MK4 and ALG are also very rigid. Wedgelock about the same as the Geissele and ALG. BCM is the “whipiest” of the five. It’s not as noticeable on a BCM 10" handguard, but the short barrel nut allows for a fair amount of flex at 13"+. URX is incredibly rigid and has good feel in my hand. Someday I’ll equip every rifle I have with a MLOK URX4! :wink:

My $.02 of experience.

NC

9

I went from an MCMR to a MK14. The MK14 is a lot more rigid than the MCMR. The MK13/14 is supposed to be stiffer than the MK8.

10

Both ALG and the true blue Gieselle rails should be super stiff. I own one of the original ALG rails and its a beast of a tube. The BCM kit is also pretty well designed.

I really dont understand whats with this: “only one rail is good for NVG’s” sauce that has been going around the net lately. When I was in we has the regular KAC RAS rails and they only had issues when the locking nut got loose. It’s definetely a MUCH worse design than anything made today, and yet worked fine enough for governemnt work for millions of GWOT dudes.

11

I’m definitely not drinking the “sauce”, but interested in how some rails compare to others. Apart from rails on issued equipment, the ALG is the only rail I have much experience with. My SPR wears a 15" Mk8, but it’s not a very good comparison to my LW build that has a barrel weighing 50% less.

12

I sure would like to see Bill Gieselle release different lengths of the MK16 handguards for the 11.5", 12.5" and 14.5" inch barrels at some point in the near future. IMHO, it is currently the best overall handguard available. I would also like to see BCM add an extra inch to the length of the KMR handguard’s barrel nut. I would easily trade a little weight gain for more rigidity. The Hodge Defense Wedge-lok rails are also some of the most rigid handguards out there. Other than being more complex and more time consuming to install and to remove the URX4 is also a fine and very rigid handguard. Personally I am not a fan of or do I trust the pinch or clamp type mounting system that is on most of the hanguards out there for hard use to retain zero, no matter whose name is on it. To many they may be good enough, but IMHO, there are better attachment methods out there. And as always YMMV.

13

What is defined as “pinch type”?

14

I have SLR rails which are great.

Consensus will likely be Geissele and the newer MLok BCM which has always had a great locking system.

15

I think with today’s tech, you will be hard pressed to find anything with Geiselle’s durability. They aren’t as comfortable TO ME, as some of the thinner, smooth rails. But, on my “ride or die” Noveske Afghan with my ATACT 1-8, you’ll find a Geiselle MK4 13” DDC rail. This is because I have ZERO concerns with it flexing, shifting, moving at all.

16

As the proud new owner of a 13" BCM MCMR rail, I’ll ask the DUMB question.

If the the optic is mounted on the upper receiver, what is the fear of rail flex - aside from the obvious (OVERflex = breakage)?

17

I think this would involve alternative aiming devices such as lasers or even backup iron sights.

18

Just a personal update as the OP: I really like the Mk14 rail. For my use, I found it to be the right profile and width. The BCM feels a hair small in my hand, though I might feel differently if I actually mounted it and took it to the range. I ended up trading the BCM 13" MCMR for a Geissele 13" Mk8 for a different project, and went with a Mk14 on my Optimum barreled primary.

War Wagon-I don’t know that there’s much of an issue if you don’t depend on rail mounted laser aiming devices.

19

Eh, I wouldn’t go that far. If you want a thin and light there are thinner and lighter. If you want a bombproof lockup and rigid tube for mounting aiming devices there are better options, some of which are lighter. Aside from cool guy cred from USASOC, the MK16 is a nearly 15oz tube with a reputation for drop damage and extreme MOA shift. Depending on your priorities, it’s solid midpack option at best IMO.

20

For example, the BCM rail and the MI Combat Rail (there are others) in that the tube is slipped over the barrel nut and then the tube is literally pinched tight around the nut without a fastener connection shared between the barrel nut and handguard tube. Conversely, on the samples I’ve installed, the ALG has both a friction fit (tight nut/tube interface) and 6 fasteners securing the rail to the nut. For the rail to turn, it would have to break free the barrel nut torque (or add to it) and then shear off the anti-rot tabs to move even further. On the “pinch” design, it is possible for the rail to shift or turn without also turning the barrel nut, anti-rot tabs notwithstanding.

Also, “pinch” sounds wimpy. I believe the industry would use the word “clamp” instead. :wink: