I have five 22 cubic inch tanks. The standard AF tank is 30 cubic inches.
The smaller tanks are 2 inches in diameter, and AF tanks are about 3.5 inches in diameter. They make it easier to see through the scope as it puts your eye lower.
They are much lighter than the standard AF tank. AF tank = 2.5 pounds with the valve. 22 cubic inch tank weighs 1.5 pounds with the valve.
A standard AF valve will not fit the smaller tank. The AF tank has metric threads — m18-1.5. The smaller tank has 5/8 – 18 english threads. I make my own valves, so it is not a problem for me.
When I hunt, I take 3 tanks with me. One in the gun, one in my pocket, and a reserve tank in the truck.
Tanks cost $43 each from Wevo Paintball – on the web. http://www.wevopaintball.com/3000psitanks.html
I was getting 40 shots with the Standard AF tank, 22 cal, standard talon valve, 12 inch barrel (with some POI drop).
With the same setup, except 22 cubic inch tank, I get about 25 or 27 shots.
Never did a formal study of it with the crony, just an “in the woods” study.