First off check the very basics:
is the gas can a new can or is at at least a third full, any less and you may start running into trouble.
It should also take about 6 seconds to fill the mag completely. Less time filling means less gas in the mag.
Is the magazine set to dry fire or do you have it sufficiently loaded? The dry fire switch should be on the left of the magazine near the round gas port. Push the follower into the mag to compress the spring then slide the switch foreward locking it down, it shouldn't be protruding out any more. Now it is in dry fire mode.
When you put it back together there is a little switch/ lever in the trigger that causes the mech to mimic the bolt picking back when empty, this may be the cause of your issue.
Take it apart and split the two halves, with the gun in semi push the biggest part, the hammer so it is flat,
Now in the right had side in front of the hammer, next to the striker is a small lever pointing up vertically to twelve o clock, push it towards the front of the gun so it's now closer to eleven o clock. The trigger should now pull crisply and the striker should strike foreward and stay there. Ensure the Mag is out when you test it.
Repeat the steps above, reset the hammer and the little lever.
Now attach the upper reciever and mate the two halves up. It should already be cocked but pull the charge handel to double check.
Now hold it upside down and dry fire it a few times without a mag while looking into the mag well. Ensure the striker comes foreward on the trigger pull and withdraws when manually cocked with the handle. It only has about 6mm travel, but it should be noticeable the two different positions.
Now load a mag set to dry fire and test it in semi. Cock it and fire it, it should have shot one shot and reset it's self ready for the next, try a second and third. Flip to auto and test a few bursts.
It's very difficult to put it into text and even a video, but it can be a little temperamental and I did have a few problems initially, simply down to me not knowing how it worked. The little lever controls a lot and the dry firing switch can cause problems too.
My advise would be to strip it down again and follow the above procedure. If something doesn't go as written, let me know at which point and we can work out the issue.
