The red cylinder is different from all the others. It doesn't have the extra "vent" hole that the others have. When I put a m130 spring into the red cylinder I ended up with an extra 10fps vs my gold cylinder. Your mileage may vary.

The springs are all interchangeable between cylinders.

They aren't standard aeg springs though. Totally different dimensions. You can get APS2 type springs and cut them down if you want a custom velocity, or you can grab a Systema one from Doubletaptactical.ca. Depends on what you're trying to do.

Just trying to drop the fps on my red from 480 to 420 (as per JOC rulez) with out spending all the $$$ on a new cylinder.

Thought I would throw this out there for those trying to make some changes with cylinders and springs.

Basic info:
- I've got 3 springs m90, m110, and m150 (Systema PTW specific)
- I've got 2 cylinders a Red cylinder with only one hole at the bottom, and a Blue one with two holes at the bottom
- 0.20g MadBull BB's used to test FPS (with hopup completely off)

So I threw all three springs into each cylinder and found that I would gain or lose FPS with the same spring depending on which cylinder I used.

The Blue one was able to get higher FPS than my Red one. Why.. could be the extra hole at the bottom, but I really cannot explain it very well.

FPS data on each Cylinder -
- The lower the spring (m90 for this case) I was able to get 300 FPS using the Red cylinder. In the Blue one I was able to get 315 FPS.
- The mid range spring (m110) I was able to get 365 FPS in the Red cyldinder and 380 FPS in the Blue
- The high end spring (m150) I was able to get 535 FPS in the Red cylinder and 560 FPS in the Blue

Conclusion:
If you plan to pick up an extra cyldiner (so long as it is the opposite and has two or one hole) and find that you are running too hot, or too low you can always swap out your spring into another cylinder to get an ideal FPS limit you are trying to achieve.


misc info:
All these tests were done with new springs, some preinstalled into the cylinders (m110, and m150), and one brand new with no tension (m90)
I cannot say the same for other users as FPS may vary from one cyldinder to another... but it's always nice knowing that someone out there did some homework for you.

in all the cylinders below red (m150)...you can swap the springs around. I had a red and black cylinder (m150 and m90) respectively...and bought the m110 and other spring (sorry can't remember) for the gold and blue power levels separately...$20-30 dollars I think (it was a while ago).

Take's about 2 min total to undo the end of a cylinder, take the spring out, swap the other in and do it up. Taking the rear end off is easier since you don't have to fiddle lining up the piston into its grooves. Taking the front off is sometimes better...to clear out crud and bb chips.

The "extra" port on the sub red cylinders is to allow the piston to build up speed before it starts to compress/push air. There's a good write up about "matching cylinders to barrel length" that explains things.

Unless I'm blind, what inner barrel length where you shooting through?

Good info, thanks. I've also heard of one case where the opposite of what you described happened (red cylinder increased FPS). I don't recall what inner he was shooting though.

Just to throw a wrench into the works here, but the spring guide has a ball in to to lock into the buffer cap. The tension on this ball is adjustable. The results of the testing could be nothing more than a difference in tension between spring guide bearing locks.

Stock inner barrel for MAX M4A1 (brand new out of the box). I'll take a micrometer to it later next week after my game on Sunday (I've got everything packed up)

I'll confirm that next week after my game on Sunday. I'll post up the exact FPS differences using max and low tensions on the spring guide locks on both cylinders I have.

Your barrel is 6.04mm. No need to mesaure.



Also, the M150 cylinder head used to have a thicker bumper. This will reduce air volume a little bit, and the lack of an extra hole means that the expansion of the cylinder head o-ring occurs a tad slower as Tyson has mentioned to keep compression speed up.

Also, how much lube is in the cylinder affects FPS. A dry cylinder, or one with overlube (grease in the piston head holes) affects FPS. At a training seminar I did, a fellow had an M130 shooting sub-300 fps, and it was erratic. I cleaned and lubed the cylinder in my own very specific fashion, and it jumped up to 350-365 fps, but still too low. I showed him cylinder lock tension, and I judged it to be a tad loose. I added 1 buffer cap shim, and it jumped up to 430 fps, and was consistant, no wild readings.

Your analysis has quite a few variables that mostly negate your findings. Don't worry about, the PTW is a different animal than your normal arisoft fare.

And this is precisely why your skilled hands are missed here Sir. Systema PTW's are still selling in this country and we do not have a PTW Doctor in Canada with your credentials.

was wondering about aftermarket parts, can i stick a magpul pts MIAD grip on it without modification?

No. You buy the real version, and you must grind it out to fit and drill and taper screw holes in the cap to allow it to stay over the motor and lock to the cap.

Agree. Just did a price compare with RW and Doubletap. Doubletap's pricing is very competitive. With shipping, customs and the hassle of ordering is well worth the price at double tap. Plus you build a relationship with the seller and in my opinion is priceless.

Mine is on order from DoubleTap....

I agree, the guys from DTT are awesome. Chris has helped me out with so much stuff and gone out of his way to make sure everything is working properly. I didn't even buy my gun from them, thats shows their dedication.
A+++++

Hats off to you fine sirs!

Get the hop-up mod done.