I purchased from a local baller a very nice Minimag with a reverse-ported, level 7 Retro valve. It also came with a 3K Flatline.

When gassed, the valve either sputters or double shoots like those old Proline autoresponse frames, and shoots on trigger pull and on release. The valve has an on/off with a filed-down pin and the valve is one of the newer ones which accepts the ULT.

What I've done so far:
-I've cleaned the valve internals, cleaned and lubed the o-rings.
-I've tried the gun with the Flatline reg (set at 1000psi) and with a Ninja 68/4500 @ 850psi
-I replaced the on/off with short pin with an unmodified one I had in my parts box
-I tried a different sear/sear pin
-I tired the valve on a different rail/body/frame
-There's a leak when holding the trigger down, so I checked the o-ring and cleaned the cavity. No improvements.

Then I decided to check my on/off's pin length and that's when I saw something odd. It looks awfully short, it's .710 instead of the usual .750. The spare on/off I has an even shorter pin, so I dunno. Think that might be part of the issue?