I blogged recently about changing my mind over a rail. The one I selected instead was the Geissele SMR MKII, and Arc Precision has been hard at work sourcing one for me. I say one, they’ve actually got five on the way – so if you want one, you’d better be quick.

I don’t know a great deal about the SMR, but I keep hearing Geissele worked with a US Department of Defense client, possibly attached to SOCOM, to develop a hard-use modular or ‘tube’ rail for the HK416…and these rails are turning up in pics of SOF in the wild. Given that many airsofters view tube rails as the preserve of race gun enthusiasts, the SMR and its military use is highly significant and is yet another indicator of what I refer to as Mil Civ – military doctrine benchmarking with and adopting competition shooting standards and expertise.

So how has the tube rail, or the ‘Brazilian’ (one strip of RIS down the middle) been militarised by Geissele and its DoD stakeholders? The SMR has to be tough and it has to be adaptable, but that’s not the whole story. Geissele provides information about the SMR MKII on their website, which I suspect hints at the criteria that had to be satisfied. I’ve pasted that info at the foot of this blog.

So why did I choose the SMR? I’ve always thought it was a cool rail. I like the brand, I like that the SMR series is based on a modern mil design and I like how the MKII looks. Having said that, a few months ago I thought I was all set for rails, so didn’t consider buying an SMR at all. The change happened because I just did not get on with my URX 3.1 and because I’d heard good things from my friend Alan, in Hawaii, about his two MKI SMRs (Alan was one of the first people to match a MKI with a PTW). Needless to say, the SMR will be used on what was my KAC build – and I always saw that as my super-premium civ build (because of the KAC theme). What better way to complement super-premium than with the most gucci rail out there?

I say the SMR is the most gucci rail out there, but clearly there’s a pecking order in SMRs because the MKII is the budget version. The reason I went for that over the MKI and the MKIV is because I prefer the look. It’s that simple.

The specific version of the MKII, sourced for me by Arc Precision, is Revision A – as pictured below. As far as I can see, it differs from the original release of the MKII in that it’s lighter. Material has been removed from the top rail and the design of the apertures on the sides of the 6 O’clock rail has changed to deliver the weight saving-  without compromising strength. I believe the MKIV version is still the lightest of the SMR series, whereas the MKI remains the heaviest (and toughest).

And lastly, why choose 9.5″? Well, I normally play woodland, and I really like to use a 14.5″ carbine in that environment. I started off my PTW career with two CQBRs and transitioned to 14.5″ barrels because I do prefer the way they handle in spacious environments. I try to avoid playing CQB sites if at all possible, but since I’ve kindly been included in Hit Takers events, I will be playing more urban. So I want a shorter gun for that.

Pics from Rainier Arms:

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Info from Geissele:

9.5″ Super Modular MKII Rail Black

The Geissele Super Modular Rail MK2 (SMR) was designed to be a cost effective option to our SMR MK1. Our SMR MK2 is designed to fit the M4 Carbine and all mil-spec AR-15 variants. The SMR MK2 was designed to do a good job in meeting the ten design specifications for a good M4 weapon rail while being a cost effective alternative to the SMR MK1.

Instead of four sharp and jagged M1913 rails spaced at 90 degree intervals, the SMR MK2 only has a M1913 rail at the 12 o’clock position while at 9, 3 and 6 o’clock is a flat mounting surface for accessory rails. The flat mounting surfaces feel much better in the hand than the sharp edges of a M1913 rail.

Accessory rails in the standard M1913 (Picatinny) configuration are provided with each SMR MK2 so accessories can be mounted where the shooter desires. Two short and one long accessory rail are provided with each SMR kit. There is also a QD mount at the receiver end that accepts an industry standard QD swivel.

The weapon barrel is completely free floating when an SMR MK2 is mounted. No force is put into the barrel from slings or bipods that could effect point of aim.

The SMR MK2 is machined from a semi-billet extrusion made from aircraft grade aluminum. A semi billet extrusion is designed with extensive machining stock for 3D features that are machined directly into the rail so that the rail is one integral piece.

Current infantry doctrine makes extensive use of accessories that require attachment to a weapon rail. Flashlights, visible and infrared lasers, night vision and thermal sights all require a rigid weapon rail so that zero is not changed when a bipod or sling is used to support the weapon from the rail. The SMR MK2 is a rigid interface for weapon accessories due to its precisely machined proprietary barrel nut and secure rail interface and clamping arrangement.

Use of aircraft grade aluminum and high strength steels in the SMR MK2 give the entire assembly a good strength and performance to weight ratio. The 9.5″ MK2 Mod 1 weighs 13.33 ozs. with the steel barrel nut. The MK2 has good balance with the center of gravity of the rail biased toward the receiver for good weapon handling characteristics.

Accessory rails are fastened to steel slide nuts instead of imbedded steel inserts like the MK1. The slide nuts are fully captured in channels configured in the rail ID. Slide nuts are much more soldier proof than inserts as a cross threaded screw can easily be repaired with the replacement of a slide nut. It takes literally seconds to install or remove an accessory rail without standing on your head to deal with non-captured plate nuts.

The SMR MK2 accessory rails have machined in shear lugs that are a close fit into the cooling slots that are machined into the rail. Any force imparted into the accessory rail is transferred directly into the rail and bypasses the mounting screws. This means that the mounting screws only need to hold the accessory rail on and not resist side loads that can make the screws loosen over time.

Each SMR MK2 comes with a precisely machined, 2-1/4” long alloy steel barrel nut (same as the MK1) and a combination wrench that will remove the stock barrel nut and install the Geissele one. The Geissele barrel nut needs no indexing to the gas tube so installation is a snap with just a torque value used for tightening. The rail is then slid onto the barrel nut and the precise barrel nut to rail fit precisely aligns the rail to the barrel. After indexing to the receiver rail two mounting bolts are tightened and the rail is secure.

Just by loosening two screws and one of the indexing screws the Geissele SMR MK2 can be slid off the barrel nut for cleaning or gas system maintenance. Even a different rail with a different accessory configuration can be mounted. As quick as it is removed the SMR MK2 is can be re-installed with the precise barrel nut to rail fit maintaining sight and accessory zero.