I am trying to RT my minimag, however it will burst about 3 or 4 shots before it chuffs and I have to pull the trigger once or twice to get it to reset properly.

I'm running an X valve, ULT, Level 10. Velocity is 230 f/s.

Am I short-stroking? bolt sticking? The ULT is kind of new, does it need to be worked in more? The ULT spacers are maxed out, one more and the valve wont fit anymore.I don't know, I am kind of new to mags.

If anyone can help me I would greatly appreciate it.