11.5" BCM KMR Noveske Switchblock

[jasonfaz]

Finally finished up a project I thought I would share. This was completed as a result of a few local buddies going back and forth about what barrel length is best for a shorty 5.56. While the Novie SB was a popular system, their wasn't an 11.5" upper offered from the factory and the SWS rail is a bit of a beast from a weight and OD standpoint. Hence, I decided to machine a KMR (a pain in the ass) to fit a switchblock and drum up a 2.9lb 11.5" upper. She shot extremely accurate, although not more so than my 10.5", but had a slightly smoother recoil impulse with the additional dwell time. At the end of the day, deciding between the softer recoil impulse and a more compact weapon is the call of the individual behind the gun, but I'm sticking with the 10.5". All I need to do now is mill out a 9" KMR as that weight savings made all the difference. The next test we're going to do is a comparison between a 14.5" switchblock cut down to 13.25" in a Vltor VIS-KM and the 10.5" SB with KMR. I'll throw up results when that's all ready to go...

 

[jasonfaz]

And we'll throw an 8" Wylde in there with an Adams Arms XLP gas piston and M4-2k set up on a KAC rig. We'll get it all on video and track pressures, accuracy variations, recoil output, and the more static components (weight, length, balance, etc)...

 

[CWD]

Looking forward to your report!!

 

[Kamkaze]

Finally finished up a project I thought I would share. This was completed as a result of a few local buddies going back and forth about what barrel length is best for a shorty 5.56. While the Novie SB was a popular system, their wasn't an 11.5" upper offered from the factory and the SWS rail is a bit of a beast from a weight and OD standpoint. Hence, I decided to machine a KMR (a pain in the ass) to fit a switchblock and drum up a 2.9lb 11.5" upper. She shot extremely accurate, although not more so than my 10.5", but had a slightly smoother recoil impulse with the additional dwell time. At the end of the day, deciding between the softer recoil impulse and a more compact weapon is the call of the individual behind the gun, but I'm sticking with the 10.5". All I need to do now is mill out a 9" KMR as that weight savings made all the difference. The next test we're going to do is a comparison between a 14.5" switchblock cut down to 13.25" in a Vltor VIS-KM and the 10.5" SB with KMR. I'll throw up results when that's all ready to go...

Very nice I am planning to build something very similar to the 11.5" upper you built, good to know you liked it.

 

[Cobracutter]

Looks good but what's up with the airsoft grip and stock? Why not use a rail that had a larger I.D. So you can run the can under? The Kmr is nice but it limits what you can do.

 

[jasonfaz]

My man CC! What's up brother? I like my airsoft parts, they're real nice. I used them because they're light.

You'd have some issues getting to the ratcheting mechanism running an M4-2k under a rail. It can be done though. I ran it under a KAC URX4 on one build which proved to be a really bad idea. The can would heat up the handguard in a matter of minutes. Couldn't shoot without gloves and even with them on you could feel the temp change real quick. It also made attaching keymod accessories extremely difficult on any part of the rail covering the can. Looked cool as hell though, just not practical.

IMO the only reason you'd want to cover the can is to extend the grip surface for your support hand out as far as possible towards the muzzle. The 10.25" KMR allows me to do so with a slight bend in the elbow. Really no need to cover the can and add more weight with a longer handguard.

Large OD handguards are for pussies anyways man....?

 

[Cobracutter]

Yea the switch block cutout is slick. Looks like the perfect setup imo. That's exactly what I would use for a build as well if you plan to run suppressed and Unsuppressed on the same gat.

 

[Cvarney]

I just completed almost the same build. You milling definitely looks better than mine. I had to go a bit larger than I wanted to. I couldn't get the gas block off the gas tube and with it I couldn't get the assembly inside my KMR rail without removing as much. Still had to work it in. Definitely like the outcome of yours better. Great looking rifle.

<a href="http://s1076.photobucket.com/user/cvarney10/media/SBR2_zps96cc80c1.jpg.html" target="_blank"><img src="http://i1076.photobucket.com/albums/w460/cvarney10/SBR2_zps96cc80c1.jpg" border="0" alt=" photo SBR2_zps96cc80c1.jpg"/></a>
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[jasonfaz]

Thx CV. I think the KMR is machined in a way that makes it pretty difficult to make precise cuts and ensure everything comes out looking like it was designed that way. I find a BUNCH of fore ends easier to mill out. In order to get the SB into the KMR I had to remove a hair under 2mm of material from the 6 o'clock position of the gas block. Luckily it's a set screw/pinned GB, wouldn't have been able to make it happen with the clamp on...

 

[Cvarney]

I didn't even think about trying to remove anything from the actual switchblock. Granted I was dremeling it. I doubt I could have make it look even half way decent. I called Novekse about trying to figure out how to disassemble the SB but they wouldn't help me. Said it had a lot of proprietary parts and what not, which I understand. I'm trying to figure out a way to modify some extra rails I have to kind of cover the exposed gastube a little better (and give me some shieldind from the heat) or maybe try to fab a little cover.

If I may ask, what did you do to refinish the rail where it was milled?

 

[jasonfaz]

I sandblasted the entire rail with 80 grit aluminum oxide. I took 100 grit emery cloth and hand sanded the edges to smooth them out, and finally Cerakoted the rail with oven cure Armor black. I'm pleased with how it turned out.

Here's an example of the same type of refinishing I did for a gentleman on this forum that wanted to run a Knights URX4 on a Noveske 8.2" 300 BLK but wanted it cut to within a couple millimeters of the thread on brake so that it looked like a monolithic set up.

 

[jasonfaz]

....and he wanted it lightened up a bit so I countersunk holes between the T-hashes and the rail came in at 7.65" and 6.9 ounces. Extremely solid rails that take heat 100 times better than do the KMRs. If i were to do it again id use the URX4 with the Switchblock rather than the KMR.

 

[jasonfaz]

One more thing... Since Cobracutter hurt my feelings last time around with respect to my choice of grip and stock I feel I should mention what worked best for me after putting a solid 500 rounds through it.

I tried the NEA CCS which was way to short to get a consistent cheek weld and sight picture and wound up using the LWRC UCIW set up but I tossed the H2 weight buffer and spring they include with that kit and went with a Slash's 5.5 oz buffer and XP spring. I also switched the JP carrier out for a PWS Enhanced DI to increase dwell time and reduce gas blow back. It is literally the perfect combo...

 

[MicroMOA]

Here are some pictures of some customer builds using my patented, tool-less adjustable gas block.
Below is a picture under a BCM KMR using a two position regulator plate for just suppressed/un-suppressed - NO mods:

Another picture under a BCM KMR from another customer using a 3 position regulator plate setup for optimal-unsuppressed/suppressed/adverse-unsuppressed, customer had to mod the rail slightly as seen below:

More pics, info and video at: MicroMOA - Home of the Govnah - Modular Adjustable Gas Block