Here's a new video test done by WGC Shop with the Dynamix custom upgrades to the Umarex/VFC UMP Gas Blowbacl SMG using 0.2g BB, powered by green gas at 359FPS/1.2J. Shown are the Dynamix Aluminium Bolt Carrier which weighs about 150g for speed and reaction, and the Dynamix Zinc Allow Bolt Carrier which weighs 350g to get that heavy recoil kick feeling.

The Dynamix version can be used for Gas Blowback beginners or for shooting competitions and according to WGC Shop the test units come with rails,  and stainless steel outer barrel.