Syrac Ordnance recently introduced their new gas piston system for AR-15 type weapons. It is available with different length pistons to fit pistol, carbine, mid length and rifle gas systems. The features that set it apart from other AR-15 piston systems is that it is both low profile and adjustable. The gas block and piston design are smaller than most other piston systems allowing it to fit under a wider variety of hand guards. There are still some hand guards that it won’t fit under, because it is still just a bit taller and a bit wider than a low profile direct impingement gas block. But it does widen the options for those wanting to do a piston build.
The adjustability is another new feature of this system. Adjustable direct impingement gas blocks have become very popular in the last few years and it makes sense that someone would apply the same idea to a piston system. This allows you to tune down the gas pressure in order to run the BCG only as hard as you need to, which reduces wear and recoil. There has been quite a bit of interest in these new piston systems, so I wanted to get you some good pictures for a closer look at the components. The kit includes the gas block, gas piston, piston return spring, bolt carrier and two Allen wrenches. It does not include a bolt or other carrier parts, so you need to supply those separately.
In the close up of the bolt carrier included in the kit you can see that it is very nicely made and is certainly above average quality. It has a melonite, aka salt bath nitride, finish which is very even and good looking. The machining also looks top rate with zero sharp edges anywhere. It is far better than your average AR-15 carrier or Mil-Spec carrier. It has the Syrac Ordnance logo laser engraved on the side and has supporting skids at the bottom rear end to reduce carrier tilt as the piston strikes it. The carrier key is machined as an integral part of the carrier and has a rounded indentation that matches perfectly with the rear end of the piston.
You can see left and right side views of the gas block below. It mounts using a clamp on method with 3 Allen head screws which is easy for the average gun builder to install and provides for a strong mount and a very good gas seal. They also make a pin-on model but it needs to be installed in the factory. Some claim that for something that cannot be knocked out of alignment, a gas block should be pinned. But if it is a low profile system that is under your aluminum hand guard, it is very well protected and you would have to break your aluminum hand guard before it could get impacted. Furthermore, clamp on systems are very strong since they grip across the entire surface by squeezing onto the barrel instead of just pressing up from the bottom. It is stronger than the set screw method for this reason, and the gas seal is usually the best with this method. On the top is the gas cylinder with the gas plug in the front which simply unscrews to remove the piston and spring for cleaning. The larger Allen wrench is used to unscrew the gas plug. Below the gas plug is the gas adjustment screw. It is adjusted using the smaller Allen wrench and it has click adjustments for predicable settings that lock into position. Gas settings can go from completely open to completely closed. You can’t increase gas pressure, since that is determined by the size of the gas port in the barrel. But you can decrease pressure as much as you want to find the sweet spot for your gun and ammo. Gas is released from the two small holes in the top of the gas cylinder that you can see below.
The piston is a simple design with a cylinder shaped head and a shaft. A small return spring fits behind the piston head to return it into battery after it strikes the bolt carrier. It’s about as simple as you can get. Below you can see the rounded end of the piston shaft which is what strikes the bolt carrier key. The carrier key has a rounded surface that matches the piston rod so that it strikes in the same place each time.
Below is a closer look at the gas plug when removed from the gas block, and you can see the gas adjustment screw below that. Next is a view of the rear of the gas cylinder with the piston rod coming out of it.
Syrac Ordnance did a good job on this system. The design is simple, the parts are well made, and it provides features that shooters wanted. They are available at http://www.nokick.com.