View Full Version : Replace 10" KMR Alpha - Which M-Lok rail?
gunf1ghter
08-23-16, 11:13
I have three BCM uppers with the 10" KMR alpha and I've got the fever for the flavor of the Pringles, err M-Lok with one of these uppers after messing with a buddies M-Lok setup.
What to buy? I like the seven sided shape of the KMR a lot so am looking for something as close as possible in M-Lok. I may or may not swap the gas block at the same time to an adjustable since my Griffin Recce 5 gets out of jail soon.
I was going to get the Geissele MK8 but it is just a little heavier and chunkier than the KMR. At least from what I've read.. Nobody local to me sells them.
Another option is the 10.5 Midwest Industries rail.. Not sure if it will allow enough clearance for the suppressor but they make a 9 inch model also. My local armorer loves them but I don't see much comment on them online one way or the other.
I would consider the new 10" URX4 but according to KAC website it is heavy as hell and you've got that whole proprietary barrel nut that requires a $150 wrench. So, yeahhh.
Any thoughts from the brain trust?
I just did the midwest lw g3 mlok rail. What is your barrel? I love the MW because i can use the magpul surefire tape switch mount at 12 oclock.
The mw seems to work fine.
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gunf1ghter
08-23-16, 11:38
It is a factory 11.5 BFH BCM upper. The muzzle device is the Griffin mini brake.
The SLR Ion has that same sort of 7 sided profile. I just put an 11" Solo Lite on a 12.5" and it's a pretty darn nice rail IMO....
This is my midwest rig. A 10.5 barrel is under the rail, and a 12" has an inch of proud.
12"
http://uploads.tapatalk-cdn.com/20160823/33faaa01cd281d523b46ae3d5b70cb59.jpg
10.5
http://uploads.tapatalk-cdn.com/20160823/55ad829ad32da4da11dbc077c4aa62cc.jpg
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I went with an 8.5" URX4 M-LOK on my 300BO and a 14.5" URX4 M-LOK on my 16" Recce carbine . Installation was pretty straight forward and the best part was not having to torque a barrel nut.
gunf1ghter
08-23-16, 13:42
Any downsides to the Midwest rails? I thought awhile back I saw complaints that they didn't adequately prevent turning of the barrel nut with their design if the rail got beaten on.
ALG Defense MLOK EMR. They're very affordable and have solid lock up and very well machined.
https://c6.staticflickr.com/4/3762/20136009685_1355982fb1_b.jpg
gunf1ghter
08-23-16, 13:57
ALG Defense MLOK EMR. They're very affordable and have solid lock up and very well machined.
https://c6.staticflickr.com/4/3762/20136009685_1355982fb1_b.jpg
ALG makes good stuff, just not a fan of the cylindrical "round rail" shape.
masenomics
08-23-16, 14:00
I also recommend the ALG defense Mlok rails, they're very affordable, and have a great barrel nut and rail attachment method.
Sorry was typing this while you responded.
PrivateCitizen
08-23-16, 14:10
I would consider the new 10" URX4 but according to KAC website it is heavy as hell and you've got that whole proprietary barrel nut that requires a $150 wrench. So, yeahhh.
Incidentally, the URX 4 Mlok weighs about 10.5 oz and has an integrated barrel nut. It also comes with the armorer's wrench/nut. So you might take a second look.
Personally I am really wishing Daniel Defense would release their MRF SLimRail XS (10" Mlok they had at SHOT). It was due Q2 and I have a naked 12.5 build that really needs a set of trousers before he can go outside.
If I have to bite the bullet I will probably get an SLR Ion Lite (they come in about every length conceivable) or the URX4 10.75.
The latest mw has a key to prevent rotation
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https://www.griffinarmament.com/category-s/1861.htm
556BlackRifle
08-23-16, 14:49
SMOS M-Lok version $195. The 9.1" version weighs in at 10.8oz with hardware. Link (http://www.smosarms.com/collections/rails/products/9-inch-gfy-mlok-rail)
The Noveske NSR - M-Lok version is about $250ish. The 9" version weighs in at 8.7oz w/barrel nut, but is currently out of stock. Link (http://www.noveske.com/collections/parts/products/noveske-nsr-mlok-rail)
You can call Noveske to check availability at 541-479-6117
556BlackRifle
08-23-16, 14:58
Another option is the EraTh3 M-Lok handguard. I have one (12") on my lightweight build and I love it. Link (https://www.rainierarms.com/erathr3-m-lok-handguard)
https://www.griffinarmament.com/category-s/1861.htm
I just picked one of these up for a new upper and it is pretty much a Noveske NSR, but Griffin has integrated the sling swivel cups into the rail/barrel nut. The Griffin barrel nut is also a bit lacking when it comes to how it is heat treated. Other than that, I really like the rail.
Defaultmp3
08-23-16, 15:44
I would consider the new 10" URX4 but according to KAC website it is heavy as hell and you've got that whole proprietary barrel nut that requires a $150 wrench. So, yeahhh.For an 11.5" barrel, KAC also has a 10.75" URX 4. The URX 4 comes with the installation wrench (which is not the same as the URX 3.1 wrenches). The only real issue, IMO, is that the OD of the URX 4 is a bit larger than the KMR. It's really not all that heavy, considering how it's a fair bit beefier than the KMR/KMR-A.
Depending on you budget, I'd also consider the Mega WedgeLock, VSeven Enlightened M-LOK, SLR ION Lite, SMOS GFY, Midwest Industries G3, and Centurion Arms CMR M-LOK.
I have three BCM uppers with the 10" KMR alpha and I've got the fever for the flavor of the Pringles, err M-Lok with one of these uppers after messing with a buddies M-Lok setup.
What to buy? I like the seven sided shape of the KMR a lot so am looking for something as close as possible in M-Lok. I may or may not swap the gas block at the same time to an adjustable since my Griffin Recce 5 gets out of jail soon.
I was going to get the Geissele MK8 but it is just a little heavier and chunkier than the KMR. At least from what I've read.. Nobody local to me sells them.
Another option is the 10.5 Midwest Industries rail.. Not sure if it will allow enough clearance for the suppressor but they make a 9 inch model also. My local armorer loves them but I don't see much comment on them online one way or the other.
I would consider the new 10" URX4 but according to KAC website it is heavy as hell and you've got that whole proprietary barrel nut that requires a $150 wrench. So, yeahhh.
Any thoughts from the brain trust?
Let me ask you a dumb question... You like the KMR's weight, shape and attachment method. Why do you want to change it? Does the the M-Loc kool aid taste that good? I just don't see what M-Loc does better.
I did both mlok and keymod. Functionally the same, but the mlok accessories from magpul were great.
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I handled a rifle with the Geissele rail last night and I liked it. It seems well made and solid, a bit heavier duty than my KMR. But I don't see any reason to go to M-Lok. KeyMod stuff works great and I've yet to find anything I want that's not available that way.
BumbleBeeGIXXER
08-23-16, 16:05
Geissele MK8 would be my recommendation. I had some of their keymod rails before they went M-Lok and they were solid
check out the v7 enlightened mlok rail.
gunf1ghter
08-23-16, 16:52
Let me ask you a dumb question... You like the KMR's weight, shape and attachment method. Why do you want to change it? Does the the M-Loc kool aid taste that good? I just don't see what M-Loc does better.
Well, I do like the KMR, I like it a lot (after all, I do have 3 of them). I did not post that I like the attachment method. Keymod is not bad, but after playing with an m-lok setup I can see the advantages it has over Keymod.... several of the accessories I messed around with attached more solidly, I liked the Magpul rail panels... as someone with a lot of Keymod stuff, I have to admit that M-Lok might be a bit better. Not sure if that meets the definition of "drinking the koolaid" but yes, I'm interested.
Had a chance to finger one of these last weekend. https://nordiccomp.com/categories/new-handguard/
ExplorinInTheWoods
08-23-16, 20:04
REV arms has a super light rail in m lok you might want to look at
I am about to replace a BCM KMR with a SMOS GFY rail. Similar diameter, Mlok and much stiffer/stronger. (If you have a KMR-A i doubt you'll gain strength or stiffness but my original KMR is like a wet noodle.)
I would wait for the MLOK CMR.
I handled a rifle with the Geissele rail last night and I liked it. It seems well made and solid, a bit heavier duty than my KMR. But I don't see any reason to go to M-Lok. KeyMod stuff works great and I've yet to find anything I want that's not available that way.
From an end-user standpoint, M-LOK is a stronger attachment interface. But that almost doesn't matter compared to the following two points: 1) M-LOK is much, much faster to machine (read: significantly lower cost for manufacturers), and 2) Magpul is making M-LOK accessories, not KeyMod, which means M-LOK wins. KeyMod had a 2+ year head start and still fell on its face from an accessory/support standpoint. Simply put, buy M-LOK rails now and sell your KeyMod rails while they're still worth something.
Geissele Mk. 8 or ALG Defense V3
Performance attributes aside I find Mlok to be far more aesthetically pleasing. And of those I like the URX the most.
From an end-user standpoint, M-LOK is a stronger attachment interface. But that almost doesn't matter compared to the following two points: 1) M-LOK is much, much faster to machine (read: significantly lower cost for manufacturers), and 2) Magpul is making M-LOK accessories, not KeyMod, which means M-LOK wins. KeyMod had a 2+ year head start and still fell on its face from an accessory/support standpoint. Simply put, buy M-LOK rails now and sell your KeyMod rails while they're still worth something.
On a new build I could see taking a look at it but I see no reason to change out things that are working. That KeyMod hardware I have will always be worth something on the rifle and what I need is already bolted on. These things aren't really Barbie dolls to me. I don't tend to change out the clothes on existing guns just to have the latest outfit and I seldom move things between guns.
I get that Magpul drives the industry to an extent but their engineering often leaves me rolling my eyes. Look at the position of the QD socket on a CTR stock for instance. A small position change and it would have actually functioned properly.
Back to the OP's original question and some of the suggestions - I consider rails that use aluminum barrel nuts and/or that require shims to be non starters. Again, that's just my thoughts on the matter. Others find those things perfectly acceptable.
Defaultmp3
08-24-16, 10:02
I get that Magpul drives the industry to an extent but their engineering often leaves me rolling my eyes. Look at the position of the QD socket on a CTR stock for instance. A small position change and it would have actually functioned properly.How does it function improperly?
I consider rails that use aluminum barrel nutsAny particular reason you're against aluminum barrel nuts? The Geisseles have an aluminum barrel nut, and I've not heard any issues with them dealing with their choice of barrel nut materials.
How does it function improperly?
Any particular reason you're against aluminum barrel nuts? The Geisseles have an aluminum barrel nut, and I've not heard any issues with them dealing with their choice of barrel nut materials.
The QD socket on a CTR is recessed and so close to the edge of the recess that you can only use a very narrow sling swivel. Anything wide enough to accept a common width sling jams against the sides of the recess and it will no longer rotate. A small and simple position change would have fixed that. Who knows, maybe it was their intention but it doesn't make sense to me.
Agree, I haven't heard of issues with the Geissele rails. The aluminum nut/shim thing is as I said a personal preference. I don't care for the need for shims and nut timing since there are obviously a ton of ways to do it that are secure and don't require either. Steel nuts torque up properly and easily during assembly. They don't seize up or gall with the use of the proper anti seize compound. They're similar to the original barrel nut design ( steel threaded onto aluminum ) so the torque specs for the original barrel nut should apply.
Defaultmp3
08-24-16, 11:13
The QD socket on a CTR is recessed and so close to the edge of the recess that you can only use a very narrow sling swivel. Anything wide enough to accept a common width sling jams against the sides of the recess and it will no longer rotate. A small and simple position change would have fixed that. Who knows, maybe it was their intention but it doesn't make sense to me.IIRC, the placement was done to provide limited rotation of the QD, instead of having to put in actual limited rotation QD cups; I know this was mentioned for the MOE SL stock, anyway, not sure if the CTR was a design oversight that got spun into being a "feature", or an actual design decision, but it's actually something I quite prefer over a QD cup so far out that it would rotate freely.
Geissele Mk. 8 or ALG Defense V3
The ALG rails have a round profile, rather the squared off profile of the Geissele. It is a heck of a value though, and includes the wrench.
IIRC, the placement was done to provide limited rotation of the QD, instead of having to put in actual limited rotation QD cups; I know this was mentioned for the MOE SL stock, anyway, not sure if the CTR was a design oversight that got spun into being a "feature", or an actual design decision, but it's actually something I quite prefer over a QD cup so far out that it would rotate freely.
It might have been intended. <shrug> But where it sits and how much or little it swivels depends on how wide the sling swivel is. I have one of those stocks and like it as do all the other people that I know with them. So it's hardly a show stopper. But it did make me scratch my head as to why.
The ALG rails have a round profile, rather the squared off profile of the Geissele. It is a heck of a value though, and includes the wrench.
The newer ALG Defense hand guards have the M-LOK sections "flattened" for accessories to fit flush. I find the ALG hand guards to be more comfortable than the Geissele hand guards, but that's just me. One thing to note, although the ALG includes a wrench, it's designed to be used with shims and installed without a torque wrench, and you must time the barrel nut. The Geissele hand guards also include a wrench, but the barrel nut does not have to be timed.
https://c1.staticflickr.com/9/8700/28910635015_95860fbf93_z.jpg
gunf1ghter
08-24-16, 12:12
You guys have given me a ton to chew on. Will start researching the options I hadn't thought of.
Very neat, thank you for the correction. I've apparently got an older set that is rounded at the attachment points. I was worried that this would cause mounting issues, but an Ariskara inline mounts up tight with no wobble at all.
I agree with you, the ALG rail is supremely comfortable. Nice and thin profile.
I run a Railscales grip panel and a Magpul Surefire tape switch mount on my mk8 Geissele where my hand rests at the 10 and 2 o'clock positions for a more "rounded" feel. I originally liked the squared off feel for my tiny, soft Boy Scout hands, but that has evolved since for a more rounded grip preference. Seems to work for either preference; be it rounded or squared off. Just some food for thought.
*Pic for ego boost*
http://uploads.tapatalk-cdn.com/20160826/118f2bfa2449b7b6f29f4e798e449e99.jpg
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gunf1ghter
08-25-16, 23:23
Thanks Large, what hand stop are you running?
Thanks Large, what hand stop are you running?
Karve by Railscales
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I get that Magpul drives the industry to an extent but their engineering often leaves me rolling my eyes. Look at the position of the QD socket on a CTR stock for instance. A small position change and it would have actually functioned properly.
The QD position on the CTR was, in my opinion/inside understanding of Magpul, an oversight. That stock was designed before the company really solicited feedback from and employed serious end users. It's not a horrible thing, but I guarantee it would be done differently if the CTR were being designed today with their current crew.
Back to the OP's original question and some of the suggestions - I consider rails that use aluminum barrel nuts and/or that require shims to be non starters. Again, that's just my thoughts on the matter. Others find those things perfectly acceptable.
I disagree. A properly designed aluminum barrel nut attachment system is very robust. I feel like this is the "plastic magazines are shit" argument all over again just because some of the early designs were crap.
I disagree. A properly designed aluminum barrel nut attachment system is very robust. I feel like this is the "plastic magazines are shit" argument all over again just because some of the early designs were crap.
Naw, it's not my argument here. Some of the rail systems look to be of dubious design and construction, others look to be very well designed and engineered. That's irrespective of the nut material. No shims, steel nut, no clocking are as I said my personal preferences. Known durability and ease of proper assembly have much to do with it. But looking at that Geissele rail a few nights ago it appeared to be a well thought out and well made product even if it didn't check off all the boxes.
Different engineers have different ideas about how things should be done. As often as not there's more than one way that's 'right'.
Naw, it's not my argument here. Some of the rail systems look to be of dubious design and construction, others look to be very well designed and engineered. That's irrespective of the nut material. No shims, steel nut, no clocking are as I said my personal preferences. Known durability and ease of proper assembly have much to do with it. But looking at that Geissele rail a few nights ago it appeared to be a well thought out and well made product even if it didn't check off all the boxes.
Different engineers have different ideas about how things should be done. As often as not there's more than one way that's 'right'.
the "right" way is the one that covers all the requirements you're given [emoji14] lol
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gunf1ghter
08-26-16, 12:38
Naw, it's not my argument here. Some of the rail systems look to be of dubious design and construction, others look to be very well designed and engineered. That's irrespective of the nut material. No shims, steel nut, no clocking are as I said my personal preferences. Known durability and ease of proper assembly have much to do with it. But looking at that Geissele rail a few nights ago it appeared to be a well thought out and well made product even if it didn't check off all the boxes.
Different engineers have different ideas about how things should be done. As often as not there's more than one way that's 'right'.
Can you give a couple of specific examples from this thread that meet your requirements? MK8 seems to meet all of them other than the barrel nut material being aluminum instead of steel.
the "right" way is the one that covers all the requirements you're given [emoji14] lol
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I always assume my way is 'the right' way. At least for me. :D
Can you give a couple of specific examples from this thread that meet your requirements? MK8 seems to meet all of them other than the barrel nut material being aluminum instead of steel.
That's an example of one I probably wouldn't worry about holding up. It looks to me like it will but I wouldn't have thought too much about it had I not seen it IRL. Look at the locking mechanism and the overall rail construction and compare it to your KMR. The KMR is amazing to me in how strong it is vs. the weight.
gunf1ghter
08-26-16, 16:21
That's an example of one I probably wouldn't worry about holding up. It looks to me like it will but I wouldn't have thought too much about it had I not seen it IRL. Look at the locking mechanism and the overall rail construction and compare it to your KMR. The KMR is amazing to me in how strong it is vs. the weight.
The KMR is an outstanding rail. The only reason I'm considering something else on at least one rifle is I want to experiment with some of the MLOK stuff.
Assuming that I pick a rail that doesn't require timing of the barrel nut, use of shims, etc, I might even be able to remove the KMR myself and make the switch, then switch it back if the new rail doesn't blow my skirt up.
Geissele MK8 would be my recommendation. I had some of their keymod rails before they went M-Lok and they were solid
If only they came in a 10" version.
Geissele MK8, I know they dont make a 10" but it is an outstanding rail. Or the URX4 which I have in keymod. I think is the easily one of the best rails on the market but definitely not the easiest to install the gas block but I could see this being easier with mlok.
gunf1ghter
08-26-16, 22:40
Well DD was supposed to start producing their new mlok rails in 10 inches but don't ever appear to be coming out as standalone items.
I get that Magpul drives the industry to an extent but their engineering often leaves me rolling my eyes. Look at the position of the QD socket on a CTR stock for instance. A small position change and it would have actually functioned properly.
Yeap
Have noticed that with several of their stocks. The QD cup is in the wrong position and doesn't allow the sling to lay nice.
In contrast, an LWRC compact stock has a QD socket that has 90 degree stops positioned in an X pattern which allows a right mounted sling to flow over the back of the stock at a 45 deg angle and then flow over the shooters shoulder.
Magpul stocks just don't work for me when it comes to QD position. The sling gets bunched or twisted or is never laying quite right.
gunf1ghter
09-02-16, 12:45
Primary Arms had 25% off Geissele products so I picked up the MK8 9.5 for $172 shipped. Looking forward to trying it out, thanks for all the advice everyone.
Geissele MK8, I know they dont make a 10" but it is an outstanding rail. Or the URX4 which I have in keymod. I think is the easily one of the best rails on the market but definitely not the easiest to install the gas block but I could see this being easier with mlok.
G rail all the way. I have a few and they are all great. I really like the ease of install and how solid they are.
Ive also cut down a 13" to 10"...worked great!
gunf1ghter
09-09-16, 12:32
The MK8 showed up and I discovered (to my horror) that my existing KMR alpha 10" is actually a 10.5". So I wouldn't be losing .5" with the MK8 I'd be losing a full inch (insert jokes about my wife here). The other issue I have with the MK8 is that it is trying to emulate the shape and profile of a quad rail. I don't like quad rails, I like the small profile of the KMR much better (insert 2nd round of jokes here).
So, the MK8 goes back and I go back to the drawing board.
I have a basically new BCM 12.5 upper that I'm probably going to sell. Then I'm going to get the experience of building an upper from the ground up and probably build it around a DD 11.5 barrel and the midwest industries or KAC URX 4 10.5 rails.
MOLON AABE
09-09-16, 16:33
The newer ALG Defense hand guards have the M-LOK sections "flattened" for accessories to fit flush. I find the ALG hand guards to be more comfortable than the Geissele hand guards, but that's just me. One thing to note, although the ALG includes a wrench, it's designed to be used with shims and installed without a torque wrench, and you must time the barrel nut. The Geissele hand guards also include a wrench, but the barrel nut does not have to be timed.
https://c1.staticflickr.com/9/8700/28910635015_95860fbf93_z.jpg
I like the ALG MLOK Handguards I just wish they would have used an inverted Geissle Barrel nut with the locking bolts towards the 12 O'clock of the handguard.
Velocitas, Opprimere,
Violentia Operandi
bulldozer3
09-09-16, 21:25
Can anyone provide a heads up on any issues with replacing a DD MFR rail with the G mk8? Easy at home job, or does stuff need to be pulled by someone with experience doing it?
gunf1ghter
09-09-16, 21:44
Can anyone provide a heads up on any issues with replacing a DD MFR rail with the G mk8? Easy at home job, or does stuff need to be pulled by someone with experience doing it?
There are tons of YouTube videos that cover the basics. Nothing particularly complicated, you will remove the old rail and barrel nut using whatever tools are required along with removal of the muzzle device.
Clean everything then apply manufacturers directions for proper installation of new barrel nut (season threads and use aeroshell), re-align gas tube and new rail, torque all fasteners properly, re-install muzzle device.
You need a vice and a reaction rod or Magpul armorers block to do the job correctly along with all the regular tools and materials. If you will only do it on or two times in your life then pay an armorer or gunsmith to do it properly.
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