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+--- Thread: What lightweight rail for 12.5" barrel build? (/showthread.php?tid=8109)
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What lightweight rail for 12.5" barrel build? - PrecisionFirearms - 07-18-2014
We stock all sizes and types of SLR Hand guards. Let us know if you want pricing on any.
What lightweight rail for 12.5" barrel build? - Variable - 07-19-2014
Here is a pic of a 12.5" barrel with the BCM KMR10 on it.
![[Image: DtlBIrY.jpg]](http://i.imgur.com/DtlBIrY.jpg)
An Arfcommer helpfully posted it up for me in a thread I started there.
http://www.ar15.com/forums/t_6_51/428165_12_5_light_weight_build___Which_rail_to_use_.html&page=1#i4085600
Thanks "andrewz71"
The BCM KMR10 is the obvious choice weight-wise (6.3 ounces!). I just wish I could close the gap between the rail and the can a touch more. I should probably stop being such a fashion princess though.LOL
What lightweight rail for 12.5" barrel build? - Variable - 07-19-2014
PrecisionFirearms Wrote:We stock all sizes and types of SLR Hand guards. Let us know if you want pricing on any.
Thank you Sir.
I'll definitely keep that in mind while my shopping continues.
What lightweight rail for 12.5" barrel build? - BjornF16 - 07-19-2014
Would the KMR10 work on a 10.5" barrel and allow the use of a can on a QD flash hider?
What lightweight rail for 12.5" barrel build? - Variable - 07-19-2014
BjornF16 Wrote:Would the KMR10 work on a 10.5" barrel and allow the use of a can on a QD flash hider?
I couldn't day for certain (without one here to screw together) but....
10.5" Barrel -minus- 10" rail = .5" naked barrel out the front.
.5" naked barrel -minus- .6" threaded muzzle section = -.1" barrel shoulder on muzzle threads.
So (theoretically) your QD flashider would be rebated 1/10th inch into the interior of the KMR rail. The KMR is 1.3" in ID according to BCM, so it would then hinge on the OD of your muzzle attachment and where your can mounts on it in relation to that.... Of course, if the KMR10 is actually longer than 10" then all bets are off.LOL
ETA: Crap, disregard--- http://www.ar15.com/forums/t_1_1/1599595_BCM_KMR_KeyMod__Handguard.html&page=2#i46056004 It seems the KMR10 is actually 10 3/8" long, so "all bets are off"...
What lightweight rail for 12.5" barrel build? - BjornF16 - 07-19-2014
variable Wrote:eta: Crap, disregard--- http://www.ar15.com/forums/t_1_1/1599595_bcm_kmr_keymod__handguard.html&page=2#i46056004 it seems the kmr10 is actually 10 3/8" long, so "all bets are off"...
"Dammit Jim"...
I guess I'll go with the 9" KMR...I like how KMR locks up the hand guard. At BoomerShoot this year, my MI Gen2 h/g kept coming loose (and we tightened it up as much as we could stand without stripping the screws).
What lightweight rail for 12.5" barrel build? - Variable - 07-19-2014
![[Image: tumblr_n3buxpHjOC1tvo8rjo1_500.gif]](http://24.media.tumblr.com/e64a42e2368dc79373a2d0e779850b8c/tumblr_n3buxpHjOC1tvo8rjo1_500.gif)
I'll try to dig more tonight.
Good info on the MI Gen2. I'm not warm and fuzzy over some of the other rail's attachment methods either. The KMR looks rock solid in that department.
What lightweight rail for 12.5" barrel build? - explorecaves - 07-19-2014
The SLR has tabs to lock the rotation of the hand guard to the upper. Combined with the clamping design, it is pretty stabile from what I understand.
What lightweight rail for 12.5" barrel build? - txgunner00 - 07-19-2014
BjornF16 Wrote:Would the KMR10 work on a 10.5" barrel and allow the use of a can on a QD flash hider?
Based off what I can measure on my setup I'm going to say no.
What lightweight rail for 12.5" barrel build? - BjornF16 - 07-19-2014
Variable Wrote:Good info on the MI Gen2. I'm not warm and fuzzy over some of the other rail's attachment methods either. The KMR looks rock solid in that department.
Variable...I had heard issues with some of these clamp design before, but finally experienced it firsthand at BoomerShoot with sustained fire off a bipod. This Twang-n-Bang video (from your earlier arfcom thread link) made the light come on.
I will replace the MI Gen2 with a 10 or 13' KMR (or similar) and plan on getting the 9" KMR for my future 10.5" Grendel.
[video=youtube;-AjlvIsCFp0]http://www.youtube.com/watch?v=-AjlvIsCFp0&feature=youtu.be[/video]
What lightweight rail for 12.5" barrel build? - Variable - 07-20-2014
Yeah, when I saw this pic a lightbulb went on in my head:
BOTTOM CLAMP RAIL ON LEFT, KMR TOP CLAMP ON RIGHT
![[Image: 84d1be00f52255cc1d9def87036e7ac0_zps4efd7230.jpg]](http://i307.photobucket.com/albums/nn291/Variable556/84d1be00f52255cc1d9def87036e7ac0_zps4efd7230.jpg)
There are probably plenty of folks with the other rails that haven't had any trouble, but I could definitely see where it might happen. Your experience is confirmation of that.
What lightweight rail for 12.5" barrel build? - montana - 07-20-2014
BjornF16 Wrote:"Dammit Jim"...
I guess I'll go with the 9" KMR...I like how KMR locks up the hand guard. At BoomerShoot this year, my MI Gen2 h/g kept coming loose (and we tightened it up as much as we could stand without stripping the screws).
Did you put green loctite on the outside of your MI barrel nut before you installed your MI Gen 2 hand guard? I haven't had any problems after I did this.
What lightweight rail for 12.5" barrel build? - jurassic - 07-20-2014
When you buy an NSR it comes with the pin, Mega and Rainier arms uppers come with the hole predrilled depending on which one you buy. They are overpriced imo, but they are small in your hand.
m796rider Wrote:Only the Noveske factory rifles come with the pin version of the NSR. The standalone rail available for purchase does not require you to modify your upper in any way. I personally like the BCM low profile keymod QD sling mount for the flexibility it gives you.
What lightweight rail for 12.5" barrel build? - BjornF16 - 07-20-2014
montana Wrote:Did you put green loctite on the outside of your MI barrel nut before you installed your MI Gen 2 hand guard? I haven't had any problems after I did this.
Nope...but I may give it a shot as I like the MI Gen 2 h/g. (I take it you also experienced the "walk off"?)
ETA: I noticed that SLR advertises an "anti-rotation and anti-slip system" for their h/g's (which have bottom clamping)...anyone have extended bipod shooting experience with these?
The KMR appear to be the lightest of the group...can these be "Cerakoted"?
What lightweight rail for 12.5" barrel build? - montana - 07-20-2014
My hand guard started to creep forward after an extended shooting session. It continued even after I had over tightened and cracked a H/G barrel nut lug. MI replaced the hand guard free of charge after I called them and they recommended green loctite. I applied green loctite on all of our MI H/G's and none of us have had anymore problems. I have been a little concerned with these hand guards in this area but they have run with out fail so far after applying green loctite.
If the KMR wont melt at 300 degrees it can be H Cerakoted. The KMR looks like a top notch H/G. If you have any questions just call them and they will answer any cerakote questions. http://www.cerakoteguncoatings.com/about/
I have a SLR H/G but I haven't done my build yet so I have no useful experience to share at this time .
What lightweight rail for 12.5" barrel build? - burkew23 - 07-21-2014
BjornF16 Wrote:ETA: I noticed that SLR advertises an "anti-rotation and anti-slip system" for their h/g's (which have bottom clamping)...anyone have extended bipod shooting experience with these?
The SLR rail has anti rotation tabs that fit onto the upper reciever. They don't work on some billet uppers like Mega's. I haven't had mine for long but to try an answer your question I twisted the handguard as hard as I could and it twisted slightly before the tabs stopped it by hitting the receiver wall. But this took a lot of force to do and I doubt it'd be possible to twist with bipods.
![[Image: D5201A59-E609-4FE6-89A8-75E0DE5F92DF_zps5s4p2cea.jpg]](http://i1050.photobucket.com/albums/s415/Burkesw/D5201A59-E609-4FE6-89A8-75E0DE5F92DF_zps5s4p2cea.jpg)
![[Image: 70B4DB9C-8206-4AC5-9C71-6B705092212A_zpsqhdyvdk3.jpg]](http://i1050.photobucket.com/albums/s415/Burkesw/70B4DB9C-8206-4AC5-9C71-6B705092212A_zpsqhdyvdk3.jpg)
The last picture is how far it twisted. When I twisted it back it re-centered well.
![[Image: F9C9FC05-DECF-434E-B548-6C805DF0A012_zpsqckfz5lz.jpg]](http://i1050.photobucket.com/albums/s415/Burkesw/F9C9FC05-DECF-434E-B548-6C805DF0A012_zpsqckfz5lz.jpg)