An AK gas system is a piston-driven system and that is where it gets its famous reliability from. However, it is not adjustable for different loads. KNS Precision has unveiled their adjustable AK piston. The head of the piston has a rotating collar that opens or closes ports to relieve gas and pressure from the gas block. There are 50 positions that you can adjust from closed to full open. This amount of adjustability will allow you to truly dial in the gas system to meet your needs.
Why would you want an adjustable AK gas system?
There are a few common reasons that make it necessary to tune your gas system, including suppression, ammo, and barrel length.
Shooting an AK suppressed is a mixed bag. Besides worrying about barrel concentricity, there is no ability to control the gas blowback. Suppressors tend to increase back pressure in a firearm which leads to greater gas blowback. Yes, even in a piston-driven system you can have gas blow back. Certain suppressors and piston-driven gun combinations can have increased gas blowback.
Ammo is another reason to need adjustability. If you reload you may need to adjust your gas system to run those specific loads. Sub sonic ammunition tends to have less pressure to fly at sub sonic speeds. Some guns may not reliably cycle with such underpowered loads. An adjustable gas system could help solve that problem.
The same problem exists if you have shorter barrels. Gas systems tend to require modification to the gas system so the weapon can cycle properly. With the adjustable gas system, you could tune the performance yourself.
In the video below, KNS also mentions they will also be offering the adjustable gas piston in 6 different lengths. This is due to the variety of gas tube lengths. Tiny AKs like the Krinkovs have a shorter gas tubes and a shorter piston is required.
The KNS Precision adjustable gas piston will sell for around $100 and different length piston rods will be $20. Installation is rather easy. You remove your BCG and pop the roll pin out that holds the factory piston. Then insert the KNS piston and reinstall the roll pin.