Help with new parts for TM p90

[Merlin]

Hi all,

So instead of a new gun (perhaps that will still happen one day) I want to sort my TM p90 out. After a spring change I feel it's in need of some TLC. Fleas retimed and changed the bussing a good 18 moths back. I've noticed some stripping on the piston teeth where I believe I had the piston not sat on the runners correctly during the many times it's been opened up over the last week (spring cutting and FPS testing, then more cutting).

The end result is that it seems to struggle with anything heavier than a .2 bb now. The joules drops off considerably instead of staying at the magical 1.11j area +/- 0.01j. I'm getting 1.11 on .2s, but dropping out to 1j +/- 0.02j

I was thinking of getting something like these:
http://www8.wgcshop.com/wgc2008/main/product_detail1.php?search_From=searchItem&item=LONEX-GC-04-14&search=special&rs=p90&catid=&cat=&view_choice=b
(I'm not sure what the difference in levels mean. It runs from level 1 to level 4. The link is to the level 4)

I need a piston to go with it and I'm not sure if pistons are generic or if I can get something like this:
http://www8.wgcshop.com/wgc2008/main/product_detail1.php?search_From=category&item=PM-PT-HP&search=special&rs=AEG%20Piston&catid=1&cat=&view_choice=a

I'll need to re-grease the whole gearbox too, so if anyone can suggest the best grease and where to get it from, I would also be grateful. Anything else you want to add would be great.

The end result is to increase the range and accuracy because currently it is shocking. I'm getting out ranged by everything, including my stock GBB pistol!

[Flazzbog]

The fps drop off with heavier bbs could be due to not having enough cylinder volume to complete a shot. The heavier bb stays in the barrel longer so it's possible the piston reaches the end of the cylinder before the heavier bb leaves the barrel. When this happens sometimes the gun makes slight popping noise and the accuracy can go to shit too.

Normally this shouldn't happen with a stock P90 however if you've lost some piston teeth the piston won't be going all the way back in the first place.

I think a piston by itself will solve your troubles I'd probably just get one from reapertech. The SHS (15 teeth) ones have all metal teeth so you don't need to worry about them stripping. I'd try that first and if it's still happening it will be an air seal issue. However I'm pretty confident it's just the piston.

[Merlin]

Thank you Flazz, and also for the help via text while I was doing the spring too. It's very much appreciated.

Normally this shouldn't happen with a stock P90 however if you've lost some piston teeth the piston won't be going all the way back in the first place.

I'm not missing any teeth from the piston, but about a 1mm off one side of all of them.

I do need to re-grease the whole thing as had to clean a lot of plastic from the gears and took the grease with it.

I'd try that first and if it's still happening it will be an air seal issue. However I'm pretty confident it's just the piston.

I think it's to do with air seal. I've always noticed that it has a very loud pop/thud sound when firing. Much louder than anything else I've used before.