Low FPS and misfeeding for first 50 shots
 

Hello, I've got a G&P Fire Pig using PTS 120rnd TMAGs, and if I load to ~100, the first 50 shots or so have super low FPS, or double feeds, or don't even come out of the barrel. After that They work fine.

Happens with my Dytac Invader mags as well.

Anything I should be looking for?

Sounds like a problem I had with my gun. If I'm not mistaken, it is nozzle misalignment. Source: pesto

usually stuff to do with the nozzle... if it doesn't fit the cylinder head tightly, tappet return speed if the tappet attached to the nozzle can't come forward fast enough or is obstructed by friction (rough rails in the gearbox) or objects in its path (trigger shuttle return spring that sits under the tappet could be hit if it's not sitting centered).

Could be piston is partially shredded and not getting a full stroke.

it would sound pretty nasty if that were the case, if it sounds like it's cycling as normal then it's not the piston.

So I ripped 'er apart tonight, and re-greased it all, and noticed that the plastic teeth on the piston are kind of deformed a little.

I installed Magic Box Hopup bucking, springs, and nozzle.
After that I did a few test shots with a fully loaded mag, and she seemed to shoot just fine.
I will report my findings after I play on Sunday.

you will notice a little deformation on plastic tooth pistons, It's pretty normal, that's wear and tear. You can make the wear more even if you add a sorbo pad to correct the angle of engagement. But at this point I would just read up on AoE and then wait for this piston to fail before fixing it. No point in opening it up again if it's working.

Gun worked flawlessly after installing upgrades new parts.
Don't know what parts fixed the issue, but I'm not taking anything out to find out.
Not a single shot through 2000 bbs had anything other than what I would call a normal shot.

Issue Resolved.

It would be the hopup bucking, or nozzle, or both that solved your issues.