As anyone who has taken enough interest in this topic to read this page most likely knows, the most often stated advantage of N2 or HPA systems in paintball is improved shot-to-shot consistency as compared to CO2 systems. While I myself live in a small town where there is literally no place to fill an HPA system, Pat Chavez (email not included until I have consent) is not so unfortunate. Intrigued by the claims, Pat conducted a small test to confirm or deny the claims. I have (with permission, of course) tranlated his emails to me into this webpage.
At no time was the gun's velocity adjusted.
| CO2 | Pure Energy | |
| Average Velocity | 288.9 | 268.8 |
| Standard Deviation | 8.4 | 11.1 |
While average velocity figures have been included in the table, they are largely unimportant. What is important to this topic is the standard deviation. The standard deviation of the CO2-powered shots was significantly less than the standard deviation of the N2-powered shots. This goes completely against conventional wisdom!
So what does this mean? First and foremost it means an N2 system may not be assumed to be "better" than a CO2 system. In this case, CO2 is the clear winner! Does this mean that this will always be the case? No. It could be that the F4 (for whatever reason) just "likes" CO2 better. It could be that the Pure Energy regulator is a piece of shit (while others presumably are not). It could be a lot of things. But it certainly should be a reason to re-think whether or not you want to invest in an N2/HPA system.
Our illustrious Pat decided that the theory he liked best was that the Pure Energy regulator was to blame. To test this theory he re-ran the experiment with a Palmer Stabilizer installed for both the CO2 and the N2 systems. His procedure was otherwise unchanged.
| CO2 | N2 | |
| Average Velocity | 254.1 | 246.6 |
| Standard Deviation | 8.3 | 8.6 |
Well, well! Suddenly the line between CO2 and N2 has disappeared! True, the CO2 numbers are slightly better, but I believe the difference (between the CO2 and N2 numbers) to be within the certainty levels of the test. But this still goes against conventional wisdom that N2 is better.
My interpretation? CO2 or N2 - it makes no real difference. What really matters is that you feed the gun gas at an even pressure. This is the task of your regulator. But apparently not all regulators are created equal! At least in this case, the Palmer Stabilizer clearly outperforms the Pure Energy regulator.
"But wait," I hear you cry, "the standard deviation exhibited by the Palmer Stabilizer was not any better than that exhibited by a plain ol' CO2 bottle! Do I really need a regulator at all?"
True, the CO2 bottle by itself can be very good at providing a constant pressure. The key words in that sentence were "can be." CO2 is affected by temperature. If the temperature of the CO2 bottle is above CO2's critical temperature (304 K, 88 F), then CO2 will not exhibit the self-regulating properties apparent in this test. So if you play on a warm day, your results are not likely to be as good as those obtained by Pat.
Similarly, since the pressure presented by liquid CO2 varies according to temperature, the velocity of your gun may very throughout the day - even if it does have good shot-to-shot consistency.
So what's a player to do?
Taking into account the cost of equipment, the consistency of the gun, and the cost of refills, I would recommend the following:
What's that? How are you supposed to know what the pressure exhibited by CO2 is at any given temperature? Well, sheesh! Just look it up in your Thermodynamis text! Whatdyamean you're not a geek? Oh, well, I am a geek. I wear that badge with pride. Hang on a minute....
| Temperature (F) | Pressure (psi) |
| 88+ | It depends... |
| 88 | 1074 |
| 80 | 969 |
| 70 | 853 |
| 60 | 747 |
| 50 | 652 |
| 40 | 567 |
| 30 | 491 |
| 20 | 422 |
| 10 | 361 |
| 00 | 306 |
And for you fellow geeks, there is a more complete CO2 pressure/temperature table available at warpig.com.
