The reasons mentioned above are all good points for HPA. Another one that I really liked was the tank pressure guage. I've never seen one on a CO2 tank but everyone has one for HPA. Its such a nice convenience to know how much pressure and subsequently how many shots you have left instead of just guessing if you have enough before you go out onto the field.

Another added benefit is the quick fill nipple. It's so easy and quick to get a fill on a HPA tank. Some fields can get you in and out with a fill a lot quicker than CO2, if they have it.

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