I don’t think HAO (pronounced ‘How’) had the foggiest idea just how hotly anticipated and popular their $80USD 9.3 Mk16 Geissele SMR replica was going to be.

HAO’s Economy Line – of which the 9.3 and earlier 13.5 Mk16 rails are a part – has been a massive success story for the company. Sublimate all the stuff HAO stands for into an affordable package, then watch how first time HAO buyers – impressed with the Economy Line – can suddenly find the money to fund additional purchases in the higher priced HAO range.

It’s the equivalent of drug pushing. Get them hooked on their affordable first taste, then watch as the money rolls in from regular purchases of the full price offerings.

But it’s a no brainer for the careful consumer. Sure, someone like me may bang on about HAO quality, but it’s not until you get the stuff in your hands that you can truly appreciate the difference between HAO and other companies which (for reasons unknown to me) are perceived as high end airsoft.

I was exactly the same with my first HAO product. Sceptical at the outset until finally ordering…then receiving an item which was practically identical to the replicated product.

Of course, it’s always nice to be sure of this – which I was able to be with my second significant addition: HAO’s flagship HK SMR. That’s because at the time I owned the RS version with which to compare.

So how does HAO do what they do? It’s as much to do with the prep as the advanced machinery and processes they use in the manufacture.

With HAO stuff, you always know the starting point is the RS item.

Notwithstanding, HAO didn’t assume the 9.3 Mk16 was just a shortened version of the 13.5. Oh no. They bought a 9.3 for R&D as well as the 13.5. That’s just an example of how they work.

So, the catalyst for this article is HAO’s 9.3 Mk16 which they very kindly sent out free of charge for me to have a look at. A nice surprise when it arrived.

First of all, don’t call it a URG-I rail. There’s currently no indication the 9.3 has been adopted by USASOC, so any build using it can only ever be termed a civilian one – if you’re hung up on definitions. You can read more about the URG-I in my article here.

Secondly, I am absolutely gobsmacked by the complete and utter coincidence that my 9.3 and 13.5 HAO rails are almost exactly the same shade of tanodize.

In any single batch – let alone batches which are well over six months apart – you will see variation in tanodize. The real thing isn’t like the glitter paint VFC and TM use on their 416A5 and Delta 416, respectively, to represent RAL8000 ano. Also, it’s not the same as anodising black or shades therein, because it’s an unstable process.

On top of that, even changes in light will affect how tanodize looks. Here are outdoor (overcast and raining) and indoor (LED) pics of the 9.3 to illustrate:

As usual HAO brings to life all the little details you expect to see.

But what about the practicalities?

If you don’t have an upper that’s close to RS spec, there are some things you need to know about the Geissele Mk16 which is also true of the HAO. Despite being able to choose from a range of barrel nuts to suit your platform, HAO doesn’t compromise its 1:1 rule for the rail itself.

Note that like the RS, HAO’s Mk16 exhibits anti-rotation tabs top rear, and allen key grub screws (albeit metric, as opposed to the imperial spec of the RS) bottom rear to perfectly time the rail. Since these features interface with the upper, it’s sometimes necessary to carry out remedial work on non-spec receivers.

The barrel nut supplied with my rail is aluminium and is threaded for an RS upper (to fit a PTW). This is part of what makes the Mk16 as a whole so light and HAO’s barrel nut is a precise, no wobble fit with their rail.

Geissele has unashamedly based this nut on the HK416 one. The holes in the radius are used for tightening (HAO sells a tool separately for this job) and the channel intersects with the front cross bolt (the rear cross bolt is dropped down below this line and is for additional security).

The cross bolts are Torx, so you’ll need to find one of those too. I always smear the upper’s threads with a tiny bit of grease when tightening a barrel nut. Likewise, I lightly grease the barrel nut’s exterior before mounting an SMR. I also cradle the upper in an armourer’s receiver block before tightening the barrel nut to RS spec. HAO stuff can handle this with ease.

Another thing to note is that the Mk16’s QD sockets are cut directly into the rail’s aluminium with no steel adaptors – exactly as they are on the RS.

If you’re using steel RS QDs (and you really should be), you’ll find that steel is harder than 6061 aluminium and some wear will result. This is perfectly normal but it’s worth pointing out.

As usual, the Mk16’s index numbers are low visibility: instead of being laser etched white, they are engraved prior to the ano process. This, apparently, was specified by USASOC.

It goes without saying that HAO’s MLOK is to spec, but it’s worth mentioning as some other replicas are not – or weren’t upon original release (brand names withheld to prevent ridicule). It’s also worth mentioning that HAO’s barrel nut does not conflict with its QD swivel points when swivels are inserted (again, brand name withheld).

So what are Mk16 rails like to use? Well there were enough of them at my local last time out to know that they are – like most tube rails – really nice to use. Combined with an aluminium barrel, they make the front end really light and quite frankly they look absolutely amazing.

For me with large hand, though, they are a little too slim.

My RS Geissele HK SMR from 2014 is about the right size for my hands

Not Noveske NSR slim, but getting there.

My old Noveske build in 2013, using the RS NSR

I was a massive fan of tube rails some years ago when they were gaining popularity, so I have owned and used quite a few. Ditto RS Geissele products.

I got through a lot of RS tube rails in 2013; Midwest Industries included

While the Mk16 is not my favourite, it’s an awesome upgrade. That said, it doesn’t surpass my favourite ever SMR – the rather ugly Mk2 Mod1 Rev A, which I bought way back in 2013. Now sadly discontinued.

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