The Centurion Modular  Rail (CMR) was first shown at SHOT 2013, and was shown installed on a Centurion Arms complete .308 build.  The rail received positive reviews from everyone who handled it, but the most common question was how long it would be until a 5.56 variant was released.  

For the past several months, I've been working with the Centurion Arms .308 Battle Rifle, and the CMR rail has quickly become one of my favorite.  The over all feel and light weight provides a great balance for the .308 platform.  

Fast forwarding to more recent times, and I'm now in a position to comment on the 5.56 CMR rails.  I have had a chance to run  drills, do several installations, as well as have a friend and fellow instructor go over them with me.   Without a doubt, these are some of the easiest, if not "THE" easiest barrel nut and rail assembly either of us have ever installed.  

The Centurion Modular Rail is first being released in 12 and 14 inch versions in both the 5.56 and .308 variants.  

The 12" rail weighs 10 7/8 oz (308g), and with the barrel nut and three installation screws is a total of 13 1/8oz (371g).  Total length is roughly 12 1/2", which is normal for most rails labeled as 12 inchers.  The reason for this is that is the length needed to cover the receiver to FSB on a rifle, which is the traditional 12"/ rifle rail.  If the CMR used an old school locking collar, the actual rail would be 12" while the collar made up the difference.  

The 14" rail weighs 11 3/4 oz (333g), and with the barrel nut and three installation screws is a total  of 14 oz (398g).  

Machine work on the rails is all extremely high quality, and the anodizing is very clean.  It is evident these rails have a lot of machine time, and for people who are unaware, machine time is what is the driving force behind the end price.  This is why you see cheap, heavy rails with sharp edges being sold for low prices.  This is not a cheap heavy rail, and it does not have sharp edges.  

The sides are blended nicely, and the lightening / cooling/ vent holes are well laid out.  Anti-rotation tabs are part of the rail, and are nice and snug on each of the forged receivers we used (3 total).  There are QD holes fore and aft on each side.  

Installation of the rail is easy, and it is entirely possible we will do another article showing the various steps.  For now, we  will just talk about it a bit.  The barrel nut is grooved, and the bolts which lock the barrel nut to the rail ensure there can be no movement once installed.  The barrel nut is tightened with an old school barrel nut wrench, the type that only has one tooth.  These are pretty cheap to pick up if you don't already have one, and don't slip off like a standard barrel nut.  The other way to do it is using a spanner wrench (the pin or hook type), which should run you under $15 for most hardware or similar stores.  Torque specs are 30-80 ft pounds, which is simple when there is no need to line up a gas tube.  

With the barrel nut installed, slide the end of the rail into place.  It may take a firm press to lock it up against the receiver, and it is normal to have a tiny space in between the two parts.  Now use a 3/32 allen head wrench and install the 3 screws.  There is no need for thread locker, but you should alternate tightening each screw and side just like you would a lug nut.  Watch your alignment on the top of the rail and your receiver, but we found everything lined up perfect ever after we took it apart a few times.

The Centurion Modular Rails will be hitting your AR15 stores this month in 12 & 14" and in 5.56 and .308.  

You may notice the second picture has a Surefire Scout Light mounted, this is a prototype of one of the mounts Centurion Arms will be releasing along with the rails. 1913 sections are also going to be coming out shortly, and none of these add one pieces use backer plates or screws.

There are also some additional items coming out for this rail series, but I'm not 100% sure what I can or can't talk about. When I get more information, and verify that I can speak freely, I'll post more info and pictures.

If you have any questions, feel free to fire away, I'll answer whatever I can.  

I forgot about this thread, I've been slacking....

disregard

Hmmmm, I'm not really sure what happened there.

Hossolo posted on this page how to prevent it.  Not an issue if installed correctly that I've seen or experienced.  I also wouldn't compare Troy, but that is for a Troy thread.

As pointed out by others, the dimensions are correctly listed on the manufacturers website.  A dealer getting an email or flyer doesn't mean they are always going to remember.  

You stated in another thread that Monty told you he had informed dealers.  I'll take his word on that.  

If nothing else, this serves as a reminder to people to communicate what they are looking for when they have a custom build done.  Especially if you are getting parts coated/ painted.  I know the additional steps and time taken can be a pain, but parts change, and sometimes what you think is going to work won't.  When in doubt, double check with your assembler.  Actually, double check with your assembler even if you aren't in doubt, just to make sure everyone is clear on what is expected.