Words and pics: Tackleberry

The question has been asked, do we really need another Cylinder Unit on the market?

The short answer would be no!

However HAO are out to change your mind.

Most of what is available to buy – clone cylinders – are poorly manufactured and assembled, and do not offer any advantage over the genuine Systema unit save for price.

So where does that leave HAO’s latest offering?


Just look at it for starters.

As with everything HAO produces, it is of extremely high quality.

Then you notice the weight. It is significantly heavier than even the genuine Systema Cylinder.

Why? The Case is made from one-piece of 303 Stainless Steel.

What is the advantage of this? Strength.

The one thing that blighted the original Systema Cylinders was that the Aluminium Case would begin to “balloon” with age and use. This resulted in the Cylinders becoming stuck in Upper Receivers, or becoming impossible to insert.

Also, the continual hammering of the Piston (particularly with stronger springs) would flange-out and deform the case where the Cylinder Head fits.

HAO have increased the wall thickness slightly to further improve rigidity.

Anything else of note? Yes, is the short answer.

All components are beautifully made, as you would expect.

The fit of the HAO Cylinder in the Upper Receiver is nothing short of perfect. This shows careful attention to detail with dimensions.


Most notable is the fit of the Piston inside the Cylinder on its runners. There is little if any slop; just the right amount of free play to ensure smooth operation.

The most important aspect of this is it keeps the Piston Rack in perfect contact with the Sector Gear.

The Piston Rack is high quality with excellent Tooth Profile and Height.


The inclusion of the Thrust Bearing is welcome. Although done by other aftermarket manufacturers, it is important, and actually worth 5fps!


Any other nice touches? Yes, as it happens.


The thicker walled Case means a shallow recess has been milled into the side for the owner to apply one of the supplied Decals. The Decals being representations of the Bolt (regular M4, or HK).

Are there any negatives?

Yes, but thankfully only two.

  1. The Detent Spring in the Rear Cap is not strong enough to prevent the Cylinder from moving under use. This is being rectified right now, and will be implemented on production units
  2. The Cylinder Head does not have the usual facility for using a 22mm Spanner (or similar tool) for removal and fitting. Instead a “special tool” is required. This tool will soon be made available.

I will stress that these aren’t really big negatives, and HAO is working to rectify the Detent Spring as mentioned (sourcing a much stronger one to match the OEM).


The Cylinder was supplied to me loosely assembled as I was going to tear it down anyway, for inspection. I assembled it in the usual fashion, using Tamiya Cera-Grease HG.

The Cylinder was then installed in a known Systema PTW with CQB-R Barrel and the standard 0.20g BB. The Spring as supplied is M90.

The results were as expected for the given Spring, coming out at a very consistent 328fps.
Pretty much spot on for 1J



This takes us back to the first question: is there room in the market for another Cylinder?

The answer to that is yes!

Given the quality of components and attention to detail the HAO Cylinder stands head and shoulders above all others.

This is further cemented by the fact it is a reasonable price too, especially given the complexity in producing the one piece Stainless Steel Cylinder Case.

– Tackleberry

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