I bought one of the first Hexagon PPSh's to be made, these of course are a bit more 'dodgy' than the Ver II ones. The mag's been on and off but mostly working well for the time i've had it. We did the 'mod' by removing the screw within the mag as shown by Mr Hexagon, but we were told that filing the central bolt is a bit of a waste of time so we didn't bother with that. Now though it doesn't seem to be feeding at all really, sometimes i can push it up and forward/back hard and it will feed, but as soon as I release the pressure it will just stop feeding again. Also when I take the mag out about 4-5 BB's fall out of the magwell, which is more than usual. Any ideas? 
The central bolt mod is absolutely key to fixing the mag...the screw removal is actually the waste of time. Whoever told you otherwise was a complete gibbon.
In fact I had file a heck of a lot more off mine than shown in the youtube video before it worked fully. But now it does.
I've tried taking some material off the central bolt: about 1mm deep, but i did file the whole inner cut shape, not just a 2.5mm width. It fed quite well to begin with, but now it won't feed much except 1 or 2. What is it about the bolt that actually means the mag doesn't feed? Will the mag feed with the bolt or is it an important part of the mag? Also which way are you supposed to put the bolt in, I put mine with the indent facing the bottom of the mag, but is it meant to be side-on or something?
Cheers in advance for the help guys, and thanks to yith who pointed me in the right direction.. 
The problem is that there is a cog in the mag that when the bolt is in a particular position catches on it. One quick way to free it up is to rotate the bolt with a screwdriver a bit, he actually demos this in the youtube video.
Filing the bolt off a lot keeps it free of the cog. You have to file a lot off.
See the pic below for how much I filed off.
Ah fair enough cheers I'll have another go tonight, i did move the bolt once and i head the 'whizz' of the mag untightening itself.
