aquatrax has posted a detailed review of the HS VHS-K rifle at MP.net with lots of photos of the rifle field stripped …
Build quality looks superb. Very few machining marks on the internals. Polymer parts looks well built and tough. There are steel reinforcements inside the housing where the Bolt group rides.
The BCG group is hefty with its massive carrier tube. It serves as the housing/guide for the recoil spring and also vents air to cool the internal chamber that house the barrel.
The VHS uses some sort of a combination of both short and long stroke piston system. Gas vented thru the barrel port goes thru a small chamber that houses a tappet piston. This tappet hits the massive carrier tube which is fixed to the bolt carrier group to drive it back to cycle the eject/feed operation. BOth tappet and tappet chamber are removable for easy cleaning. The tappet piston looks similar in design with the G36 piston. It also has the 3-piece piston ring. The difference is that the VHS’ piston and push rod is one piece. WHile the G36 employ 2 separate pieces.
The tube that the large piston rides in is very big. It will suck in and blow out a lot of air as the gun cycles. They also seem to have shifted mass from the bolt carrier to the piston, which could, please correct me if I am wrong, help reducing felt recoil and/or muzzle rise.
[ Many thanks to Alex for posting the link on Facebook. ]