I have fixed a friend's with a smalish laptop screw, placed near the rear/lower edge from under, then filed the part of the head that was extending past the rear edge. Still Semi with that, as the head of the screw is about 1/2mm.

full metal rack on an AEG is a bad idea. The steel they use is too brittle to absorb constant impact

That's why it's recommended to epoxy the rack to the body. Short of the pistons binding to the rails, I've had very good experiences with SHS full tooth pistons.

Ummm... Hectic... how come no one noticed before, but how are you correcting for AoE without shaving the 2nd tooth?

John

haha good catch
but he mentioned something about the AOE being correct already, so i know i didnt even look after i read that... still wouldnt cause this problem, but would def help ur gearbox by shaving down atleast the first tooth

You know, we went years without shaving the 2nd tooth off any pistons and some of them lasted a really long time lol

if he has a Sorbo pad on the cylinder head, AOE would have to be adjusted.

im still learning.. so i cant think straight without taking my gun apart and looking at my AoE. mine is set up fine ive shaved the first tooth off mine and some of the second, this is without a sorbo.. What would happen to him if his gear tooth catches the piston too early by hitting the first tooth or the second?

Would it cause the piston to launch forward with a gear tooth still in the way?

Coach got it. The sorbo pad seemed go have it perfect. When i spin the sector by hand with out a spring or guide in the first tooth on the gear lined up with the tooth on the piston perfectly didnt seem to want to half catch or skip over to the seccond tooth or anything.
As far as i knew the sorbo and or a shaved tooth of two wer ways to correct the aoe and that you didnt always have to shave a tooth if it all lined up good good so i didnt see a need to shave it.
In hind sight looking at the piston the pickup tooth and the ones close to it look nearly new so id say the engagement was good

Just because the first few teeth, where the gear grabs, are in good shape, doesn't necessarily mean your AOE is good. Theres not enough force or speed to rip at the plastic tooth at the beginning or "engagement."

Correcting AoE with 70D Sorbo for Airsoft Aeg - YouTube
this guy has a great vid for checking your AOE

As far as i can tell you dont really need to shave teeth unless your going higer speed (like 13:1 gears on a high speed motor or runnin 11.1 lipos)
The shaving of the teeth alows the sector to grab the picup tooth then the tension of the spring increases slowimg the rotation a bit then the sector can cleanly grab the seccond or third tooth (depending what you shave)
When the sector is spinnjng real fast as it grabs the picup tooth it wants to spin faster thdn the piston is moving back so the seccond tooth on the gear will want to grab the seccond (first regular) tooth on the piston too soon and winds up chewin the heck out of it.
I think personnaly in most cases the teeth will wear out if the aoe isnt good and the issue will sort of work itself out( only downside will be the bits of plastic in the gearbox)
Im surs the gurus will chime in but thats my baisic understanding of it.
The sorbo pad brings the piston back a bit aligning the picup tooth and first tooth of the sector and sort of preloading the spring a lil so the stuff will all move at the same sort of speed.
Im sure if i threw a 11.1 jn my gun j may have to shave a tooth (or it would shave itself ) but on a 9.6 with the sorbo it was perfect.

Only one explanation.

Your AEG has become self-aware. O.O

The purpose for adjusting for AOE is so that the first tooth of the sector gear meshes with, and only with, the first tooth on the piston.

SO, if the first tooth of the sector gear touches or drags the second tooth on the piston and/or the second tooth of the sector gear on the third tooth on the piston before the first tooth mates with the first tooth on the piston, pull out the dremel.

Hectic, I think your piston is releasing early and the wear is from dragging along the last tooth on the sector gear. You're lucky you don't have more metal teeth on the piston or you may have pouched your sector gear. Check your AOE again and ensure the sector gear is not engaging the second tooth on the piston.

HAHA yes if this is the problem i feel super smart. This is why i asked that question. I watched vids and paused to figure it out and yes if your gear picks the piston up from the first or second tooth instead of the BIG TOOTH, then itll release your piston too early and your whole piston will now grind away along the last tooth of ur gear

Coach does have it

When I say first tooth on piston, I am referring to big tooth or how you put as pickup tooth.

Ok i gotta get this straight then lol
First tooth means engagement tooth

so shave the second and third