- SD nozzle
- SD piston head
- PDI 6.01 tightbore
- Stock floating valve

Question: Is the Nine Ball Dyna Piston Head better than the SD Piston Head? The SD one doesn't have vents and I'm wondering if the vents reduce the power by venting out gas instead of utilizing it for power.

I don't think the vents on the piston head affect FPS. The BB has already left the barrel when the blowback process begins. The ported piston head improves the air seal during the blowback, thus yielding better blowback response and gas efficiency.

So basically, piston heads with vents > piston heads without vents. Ok, that's good to know. The SD piston head seemed to be putting out better numbers than the Nine Ball, which is what made me wonder. Here's a short video I shot using the current setup:

- 6.01 inner barrel
- Nine Ball piston head
- Nine Ball enhanced floating valve spring
- Nine Ball hop up rubber
- SD POM set
- Enhanced floating valve

VIDEO HERE

The readout:

Chronograph: Xcortech 3200
Projectiles: 0.25g BBBastards (black)

337.6
000.0 (did not read)
324.1
330.1
328.7
328.8
325.3
328.4
324
321.5
321.8
324.8
317.6
316.2

High: 337.6 FPS / 1.32 Joules
Low: 316.2 FPS / 1.15 Joules
Average: 325.3 FPS / 1.22 Joules

Translated figures using FPS calculator if I was using 0.2g BBs:

High: 376.84 FPS / 1.32 Joules
Low: 351.74 FPS / 1.15 Joules
Average: 362.29 FPS / 1.22 Joules


In earlier tests I had the exact same set up, but instead of the Nine Ball piston head and enhanced floating valve and floating valve spring, I had the SD piston head and stock floating valve and spring. My shots were more consistent, and I also achieved more power. The results are on page 35 of this thread.

I assume your enhanced floating (rocket) valve has an oring which improves air seal, but I hear problems with the Nine Ball valve spring. While it's suppose to increase FPS, by leaving the valve open longer, I'm sticking with the stock spring. Being the stiffer spring maybe the cause to the inconsistency. Also, you changed more than just the piston head, which doesn't seem to be a fair comparison.

I did change only the piston heads before this setup, and it gave me about a 10 fps loss and a higher variance between shots and I have no idea why. The first test done using the SD piston head was performed in my basement where the ambient temperature is lower than my second test, which was conducted upstairs.

Use what works best. Just because a ported Nine Ball Dyna piston head may work better in theory doesn't necessarily mean it works best in your build... right?

Efficiency of gas usage in blowing back the slide won't do all that much in terms of performance of the BB out of your barrel anyway - only thing I can think of is that the mag valve might close a hair of a fraction of a split-second before it would have if your blowback is slightly more responsive. Correct me if I'm wrong, but for raw performance in terms of FPS consistency, how much your GBB kicks doesn't really affect that... right?

I still don't get why the SD piston head worked better. Isn't that kind of like saying that racing tires in theory should give you better traction on a flat road, but it doesn't necessarily mean it works better on your car than your other tires? I'm pretty sure you could put racing tires on any car and it would work better than normal tires.

Not when it rains/snows. :)

Try testing the two piston heads again with stock valve spring, if you haven't done so already. I assume you still have the BB in the MSH?

Damn I wish I have the luxury of conducting tests on mine. :(

I took the BB out of the MSH because I was afraid the spring would warp after a while. I'm pretty sure that'll drop the results by around 5 fps. But I'll test the different piston heads using the stock spring and report back asap.

I just thought Id point out, though not really related, I've had problems with the last 4 builds I instealled nineball piston heads onn, every time hte Oring would get blown out and jam in the nozzle assembly requiring a completer dissassembly to fix, and to just do it again 5 shots later, I get better results with stock piston heads

I found that the SD nozzle o-ring was such a tight fit that the nozzle would have a hard time slide along the BBU. When it fired, the nozzle return spring wouldn't be able to put it back into its at-rest position. I have no problems with the Nine Ball one, but it seems to shoot weaker.

Hey i have a question if u guys dont mind.. for my 5.1, the hammer strikes, but sometimes, it doesnt hit the gas bulb on the magazine so it doesnt fire.. I usually need to push and hold the magazine into the grip, in order for the gun to fire. Im using a stock grip, with SD magwell and SD magazine base. I check the the magwell and nothing is blocking the magazine from coming up in the grip. Anyone experience this issue?

I have that issue with my gun only when I try to use a 4.3 magazine in a magwell that I haven't modified to accept the short base plates yet. Maybe the notch in your mag is worn down, and the heaviness of the mag plate combined with gravity is allowing it to sit lower than its supposed to.

Yeah, as I started to use a Guarder nozzle with a Nine Ball Dyna piston head, mine started to do that too. I switched over to a *gasp* WE piston head and it works fine, lol. I think it might have something to do with a) piston head O-ring getting old/not as elastic as it used to be, or b) too much free space for the O-ring to expand, and thus it'd just get blown right off the piston and would get stuck inside the loading nozzle.

Pain in the butt, +1.

Guarder nozzle as was tested over at Airsoft-Barrack when compared to SD and stock, actually decreases the fps in most cases, its probably oversized and other issue might be cause by that...