Half toothed piston
 

I have an AK I'm moding into a SVD. The gear box is reinforced, bushings, shimmed, upgraded spring guide, 500 fps spring, and ultra torque up helical gears. The problem I'm having is that the helical gears means I have to use a half toothed piston, and I can't find a half toothed piston that will stand up to 500 FPS. I half stripped a mad bull polycarbonate half toothed piston from Airsoftparts. They cary metal pistons, but non of them are half toothed. I need a half toothed metal piston. If anyone knows where I can find one for sale please let me know. I'm looking for one that is in country, I don't want to have to wait for a pre order to go through or deal with customs.

Thanks
Bill

No, being helical does NOT mean it requires a half tooth piston.

But being ultra torque ups DOES mean that it requires a half tooth piston.

You can get standard torque and one level torque up gears in helical format that can use standard full teeth.

I can get you a Prometheus half tooth piston if you need. Hit me up by PM if you want to jump on a preorder.

Prometheus pistons are made of POM / Delrin, which is a nylon reinforced fiber polymer that stands up to wear a bit better than Polycarbonate does, which is a bit more brittle.

There are very few people who carry stock on half tooth pistons in Canada, so if you can't find one anywhere, a preorder is another option.

I'm looking for one that is metal, aluminum, titanium, etc.

Systema use to make an all aluminum body, but as far as wear goes, aluminum has poor wear characteristics compared to Delrin/POM. The heavy weight of the piston and the excessive vibrational impact it applied to the gearbox combined with the poor wear characteristics of aluminum are two contributing factors as to why nobody makes aluminum pistons anymore. Systema has since discontinued the product.

I still recommend a POM based piston body with 4 steel teeth or more.

If you're smoking your piston, chances are, there is something wrong with your setup and that problem should be corrected before you attempt to just band aid the solution with super strong parts. That will only cause another part to fail, and the next part in the chain would be your gears. Replacing your piston on a regular basis would be a cheaper proposition than constantly replacing your gear set.

There are many setups that shoot over 550fps with polycarbonate pistons before with little to no wear. There shouldn't be any reason why you can't do it either.

Changing to a metal piston does not make it indestructible. Having a proper setup will make it near indestructible.
I can show you what happens to an all aluminum piston in a poorly balanced setup. I still have the result of one that lasted less than 2000 rounds.

At 500fps, I think the gear set you are using is insufficient. You should actually be using the Infinity torque up gear set, which could be why you're having problems.

When your system is undertorqued, the motor builds up a LOT of excessive energy in the process of cranking the spring. The result is that when the piston is finally released, the motor releases all of that built up potential energy and causes the sector gear to come swinging around at a very high cyclic rate and crashes in to the end of the piston before it returns to battery. Your system sounds unbalanced.

I can recommend these two gear sets to help resolve your issue:

- Systema Infinity Torque Up Gear Set
- Prometheus Max Torque Gear Set

Both require half tooth pistons and are recommended for 500-550fps setups.

Also, what battery and motor are you using?

I have a Clasic Army High Torque motor, Ultra torque Helical Gears. The piston striped the polymer teeth before it could even fire one round.

You're gonna need more than a CA motor for 500+ FPS, sound like exactly what Illusion has described with the built up energy is happening.

Look into G&P and Systema Motors.

What battery are you using?

The built up energy issue can only occur after a shot has been fired. As he claims, not even one round was fired...

Just try a different brand. I've never used Mad Bull pistons before, so I can't comment on those. Try the Modify or Prometheus pistons instead. Like I said, it's cheaper to kill your pistons than it is to kill your gear sets.

Your gear set is Systema brand, correct?

I'm using a 9.6V, tried a 8.4, but I think it was dead. I'm using these gears Hurricane Helical Ultra Torque-Up Gear Set V2/V3 (from Airsoft parts). This motor Classic Army High Torque Short Motor (From Airsoft parts). This Hop up Pro-Win AK Hop-up unit, and this Spring Moify S140 Upgrade Spring, and a modify bearing spring guide. All from airsoft parts.

It all sounds pretty normal. I'd recommend the 9.6v battery with that set up.

Try a different piston before you go for a stronger piston. Again, you risk destroying your gear set if you go with a very strong piston. One thing's gotta give, if there's a problem and you're better off killing the cheaper of the components.

Hurricane also makes a full metal aluminum half-tooth piston that is the one recommended for use with the hurricane helical gear set that you have.

I have the same setup. My hurricane tune-up kit came with those helical gears and also the hurricane full metal piston matched to them. Another piston that works with the hurricane helical gears is a Deep Fire half-tooth piston.

All of this is a good sound theory, but this gun is most likely (or should I say hopefully) modified to shoot semi-auto only. If his switch (and the cut off for it) is working properly what you explained shouldn't be happening because the power will immediately be cut off after the piston is released. Some guns do have overspin, and with that malfunction this might just happen.

I'm going to second (or third) the Prometheus Half Tooth piston. I have one pulling back a Guarder SP170 spring at around 600 FPS at the moment and with maybe 5,000 rounds through it it's going strong (not a lot of rounds compared to full-auto guns, but that took me a LOT of shooting time to go through that many in semi-auto well aimed shots).

Sounds good but where can I get one of those pistons. I manly just deal with Airsoftparts, and would love to know where I can order more stuff from.

If you have access to a mill, I have a standard full width Prometheus piston that you can mill down, otherwise, an actual Prometheus MAX piston would have to be ordered in.