Quote Originally Posted by brassbanjo View Post
yeah there's a big difference - plenty of posts on this forum about the bore and stroke of tx200s and hw97's, something like 26mm bore x 80mm stroke, about 40cc of air.
A 12 ft PCP would need something like 3 times that much air, maybe a bit more for a .177.

Note that doesn't mean springers are necessarily 3 times more efficient than PCPs though!

BB
65.3cc's by my maths ,

As I said above, in a PCP the energy that you have put in to the springers spring when you compress it cocking the rifle for each shot, does not exist so that stored effort/energy has to come from extra compressed air.

For a given pellet in a given bore & barrel length, the energy (from the compressed air) required to reach a specified muzzle velocity will be exactly the same ( vol A), so the shot is equally efficient.

BUT to replace the energy from the spring you need another 150%ish of vol A (vol B).
All vol B does is push vol A in to the breach it then exits the muzzle as wasted air once vol A has shot the pellet out.

In a gas ram vol B is contained inside the ram, but You again have to impart the energy in to the gas by physically cocking the rifle to compress the gas for each shot.