Physics 101

[AJ3]

I am a retired engineer and its been quite a while since taking physics. Just read a question on another forum regarding changing nothing on a given air gun other than the barrel and pellet probe size from .25 to .30 cal and how to calculate the new fpe. My background tells me that keeping pressure and time of pressure release constant, fpe should remain constant regardless of the size or weight of the pellet (ignoring friction)...can not create pellet energy without some physical change to the air gun to increase discharge energy. This seems so obvious to me that wanted to check with the group here to make sure that I am not just getting old and missing something in their question.

 

[pheelgood]

This explains it well I think.
http://www.kiledjian.elac.org/phys%20001/Ballistics%20of%20Air%20Gun.pdf