Has anyone shortened a BCM KMR forend? I’m interested in using one with an AAC 9" 300BLK barrel and I want to have enough room to still use a 51T muzzle device with my can.
Anything odd or unusual about cutting whatever alloy BCM is using? I assume Cerakote is the stuff to use afterward?
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I’d make sure it was done on a milling machine for precision. I certainly wouldn’t wing it with a Dremel tool!
Cerakote or Duracoat afterwards would suffice, or you could tape it off and hit it with a little appropriately glossed black spray paint.
Why bother with a milling machine when I have a perfectly good hacksaw in the garage?
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Oh. My. God. You’re forcing me to reach for the bourbon, you know that right?
BTW, I just looked at a pic (didn’t feel like going down to my safe) and the keymod slots are staggered from one surface to the next above or below it. In other words if you straight-cut it it’ll look like shit! The cut right in front of a given slot will go right through the center of the one above or below it. You won’t have a smooth front surface to your rail.
Yeah I see the slots are offset around the rail so the hacksaw might have to go back into the toolbox.
Plan B, if I decide to go through with it, is to send the forend off to someone like Marvin Pitts. Maybe I can have him dimple the barrel while he’s got the rail in his shop.
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Go for it tokarev, it’s your money and it’s not an area vital to weapon system functionality that you’re modifying. Just take a lot of pictures and post them.
It’ll be awhile.
I’ve recently picked up a receiver set from 2A and am now wondering what to do with it. I had kind of been thinking of building a 16" carbine with a BCM or Ballistic Advantage pencil barrel. I still might just do this route but it might be pretty fun to have something short and light in 300BLK instead.
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Don’t sell the hacksaw short. In Machine Tech. school we had to get NIMs certified in precision layout and bench tools. One of the projects was a 2x2x2 cube that had to be cut and filed down to .0005 parallel/perpendicular/flatness with perfect finish, using nothing but hacksaw and a file. Teacher was so impressed with buddies and mine he kept for his student project wall. Not saying you should hack on your KMR, but hacksaw and good file with draw filing technique, can produce some pretty amazing results… Dremels are for wusses.
Funny, I just started an AAC 9" build and was thinking about cutting down a KMR or NSR.
I was unable to figure out an easy plan for the KMR. The NSR though, what if you cut the barrel nut side of the NSR 9?
Hacksaw is too much work- I’m going for the Sawzall
There might not be an easy answer. At least not for an 8" KMR rail.
Another option might be to go with a 12.5" barrel and a 10" BCM. This probably wouldn’t be as outright nifty as a 9" upper but it would be much easier to assemble.
If you can wait it out a month and a half at the most… 2A will have a 7" Solution that matches the upper on the BALIOS-lite
Mods, if this is considered out of line, please delete.
Not sure how much magnesium is in the alloy but I would be careful sawing and grinding on it. Quick lesson… How to burn down a workshop… You fabricate a couple of parts for you drag bike out of some magnesium you came across… The work involved sawing and grinding… You then put a piece of steel in you vise and hit it with a sidearm grinder… Sparks from the steel ignite the magnesium grit on the bench… last step… attempt to put the fire out with a water hose!!
This is a painful thread.
You would be much better served by buying an 8" rail.
It’s no big deal. My local handy guy hacksawed and filed a 10" for my 7.5" fun gun. Can’t remember what I blacked the edge with. Does it really matter if you have to touch up occasionally? I think it looks great with the KX5.
Yeah, that works well. Most folks with the AAC 9" go with a URX3 8.0 but I like the KMR/NSR rails.
Phreakish had a few tips here:
maybe you can do a Warsport cut? thats a thought… i’m just sayin’ 
I do plan to cut my 9", but I’m also not in a hurry.
I’ve been thinking I’d go with a non straight cut- preserve a solid edge. I was thinking Dremel followed by file then sand.
My objective is to allow the ports on my MAMS to clear the rail.
