13.7 build - BCM Rail

[Dutch110]

Doing a 13.7 build and I am in the midst of figuring out which rail I want to use. Using a BCM stripped upper so wanted to also use a BCM MCMR MLOK rail. My concern is that this rail, while measuring at 13 inches, actually extends out to 13.4 at the flared portion. Using a KNOX on this build. My concern is if I end up adding a can that I will run into clearance issues. Anyone have any experiences?

[titsonritz]

Judging from my 14.5" with 13" MCMR I'm going to say no f'n way it will work without a hacksaw.

[NoveskeFan]

I have a 13.7" pinned with a B.E. Meyers 249F, with 13" KMR rail. You'll probably need to cut the side flares back.

You can see the rifle with KMR in this video has been cut back:


Mine:

[Dutch110]

Thanks Gents. Exactly what I needed to know. I kind of figured this would be the case. So I either need to resign myself to never running can on this or go with a 12.65 rail from MI, Centurion or FCD. Or get out the hack saw.

[GH41]

Thanks Gents. Exactly what I needed to know. I kind of figured this would be the case. So I either need to resign myself to never running can on this or go with a 12.65 rail from MI, Centurion or FCD. Or get out the hack saw.

Or just do a 14.5" barrel. Why chase your tail for less than 3/4 inches of barrel.

[Dutch110]

Or just do a 14.5" barrel. Why chase your tail for less than 3/4 inches of barrel.

Couple reasons. I've already done 14.5 builds. I already have the 13.7 barrel. I wanted to try something new

[Gonz9731]

Late to the party I know. But, after several builds trying to minimize as much gap as possible your SureFire cans require roughly .7” of diff between actual Bbl length and actual rail length and your DA KeyMo mounts only need .5” diff. Hope it helps. On a 13.7” the old Geissele ACTUAL 13” Mk4-8s work perfectly with SF cans and the KAC URX4 at an ACTUAL 13” works really well also. Virtually NO gap if that’s what you’re after.

[rm06]

https://www.ripcordindustries.com/pr...age/ldr1-13-13

The Ripcord LDR1 shows it is made for 13.9" barrels, maybe you can shim the muzzle device .2"

[Gonz9731]

That’s near 1/5-1/4” could be almost half your threads.
You could also knock down that rail that much I’m sure not Sure how close that’d put you toward your first MLok slot.

[Dutch110]

I'm not worried about or wanting the rail to butt right up against the can. I just want to make sure I have enough room to add a can in the future.

I thought about cutting down a rail to fit but like Gonz9731 said that first MLOK slot would mean I would have to cut several inches off to get to clean real estate on the rail and not hack it mid slot. Not worth it the more I look at that option when there are plenty of 11 inch rails out there if I go that route. The MI Combat rail solves my problem with a 12.65 OAL. I have that rail on my 7.62 and like it. Or, if I can find one, FCD has one that should work too. If SOLGW had their wedge rail in stock I'd buy that and call it a day. I also thought about the VLTOR rail that is sort of out in there in the wild but when you do find them the 13s are sold out. Not going to lie, this is half the fun of building to be honest. Searching and researching to get the right parts that work right together.