Quote Originally Posted by brassbanjo View Post
....Note that doesn't mean springers are necessarily 3 times more efficient than PCPs though!....BB
But it does mean that for a spring gun the barrel length required to extract all the energy from the air pulse is much shorter.
A 12ftlb springer only requires about 10" barrel for .22 and 13" for .177. Rammers slightly shorter than that. PCPs about double that.

Many airguns have a barrel that isn't the optimum length for efficiency because other factors such as excessive overall length, excessive forend weight, cocking leverage or even cosmetics also influence the design.