Longer barrels

Hello all, let me get some practical knowledge from you guys. If some of you are engineers, and I know some are, then please be gentle and explain to a non-engineer type of guy ">


So, I know that a longer barrel will increase velocity, the powder can burn longer and has more "thrust". Okay and a heavier bullet (normal is usually 115 grains and so I bought 124 grains), the bullet being heavier should cause drag (?) and therefore increase pressure? And kick?


So, why do you have the possibility of the toggle not kicking enough when you put on a longer barrel.


Why?


I have a 4 inch and a 8 inch Luger and they are fine, but in my discussions with some of the guys, they said that by putting on a 6 inch barrel (being done right now )that some Lugers don't have a strong enough spring to cycle correctly?


Why?


thanks,


Ed