We ano Turtle cockers for them. But the ones I posted are my bodies with his conversions.
You can get information to contact me at www.aplusanodizing.com
We are also coming out with delrin bolts for cockers that are as light as the dart bolt but more efficent. They should be ready in a month.
Check our web site for updates.
Also BMW dude. We build low pressure cockers from scratch and a lot of the info you have gotten about low pressure is correct. We bore and port the air passages of our cocker and we use custom SS valve springs that allow low pressure operation and still offer efficentcy. We make our own valves but the Turtle valve is great and you don't need to worry about a spring because it comes with one on it. Next the AKA, Kapp Comp, RAT 3:16 or Madman work good as well, although the madman is difficult to set up if your not experienced.
What are you trying to achieve?
We also make the custom Freak tips in 8" as shown on the turtle. When you shoot 300 FPS @ 200 PSI OR lower you don't need a long barrel. I'm a back player and I use that 8" on my gun