vulcan gen?

Wasn't aware there is a third gen but would not be surprised. The gun was introduced sometime in March/April, I believe (Gen 1) but Evgeny (the owner) is intent on making the best product possible so made some modifications to the moderator and some other minor improvements in June. However, I don't know how you would tell except by serial number, enkey. As far as I have been able to determine there are no appearance cues that would tell you. Perhaps you could contact Evgeny and ask for serial number demarcations for improvements.
 
The first batch had a small bolt hammer and the linkage rod wasnt very built and the shroud system didn't work very well. So instead of a lollipop bolt they changed it to more of a cylinder shape and put different shroud internals in it to quite it down better and beefed up the linkage rod. That was the June shipment which is what I got. Then there was complaint about the ping of the gun so they put some rubberized tubing of some sort on the hammer spring to shut the ping up but not completely getting rid of it. They also did some other small thing like changing the hammer spring adjuster to an Allen head and I think it might have slow fill now, not sure though. There wasnt necesarly 3 gens but more like 2 upgrades from the original. And that was the August shipment.