VFC UMP GBB Blowback Tuning
OptimusPrime
17 Apr 2013
Now this is a nice piece of video tip imparted to us by WGC Shop via their video presenter, Leo. For those who already own the VFC UMP Gas Blowback SMG or planning to get one, here's how you can tune the SMG to provide a harder or softer kick... "This is how you can tune the blowback kick from hard to soft for your UMP GBB."