Like this.

TOP
_ NUB
O BARREL

BOTTOM

Erratic performance can also be caused by the o-ring on the piston.

One thing you can check easy is when you dissasemble your gearbox, try to see if you have a hard time pushing down the piston in the piston cylinder.

If air gets trapped by the o-ring then you have a good seal and you should feel some resistance.

If not, change your o-ring and your shots should get a normal FPS everytime through the chrony.

If you can't test what I've just written, then you have some homework to do on this site : www.mechbox.com ( it's down right now so check their youtube channel here : http://www.youtube.com/mechbox6mm )

Get er fixed up?

I'm still having problems with the nub its really frustrating because i don't know what's right.

Look inside the hop up unit. In the top section you will see a small slot the nub lays flat in the small slot.

JLS SCAR Barrel Swap in HD - YouTube

Like this
The hop unit is the same

OK i put the nub back, i saw a video and it fits awesome, I cleaned the barrel and the bucking so i will see tomorrow when the suns back up. I will see if there's any problems after that. Thanks for all the help by the way!!!

No worries we all needed to be spoon fed at some point untill we learn hkw to do it ourselves.
Besides thats what forums are for. Least thats what they are spose to be for.