OK, Big time newbie question here. When changing case dimensions and neck angle of a cartidge how drastically does that effect chamber pressures and velocity? When using the same exact weight bullet and powder how much more velocity and chamber pressure will a .300 WSSM have than a .300 Win Mag Or, let's say you have a straight walled cartridge like a .458 Win Mag. If you took that same weight bullet and same weight/type powder and turned the cartridge into a wildcat cartridge how much would that effect pressure and velocity? A 5% increase in pressure and velocity? How about the opposite. Take a 6mm PPC cartridge and use the same weight bullet and same weight/type powder in a straight walled case. How much would the decrease pressure and velocity? 5%? Or doesn't it effect velocity and chamber pressure that much by changing the dimensions of the powder case while using the same weight bullet and powder? Thank you for your time.