Rate of fire Q.

[ktime]

Hi everyone, I'm sure you guys can answer this questions for
me. On full autos what determines their rate of fire? I mean why
some machine guns can shoot 900rpm and some shoot 600rpm?
Sorry if its dum question but I would like to know.

[Cannibul]

Why is the sky blue?
Why is water wet?
Why?

There are MANY things that determine the cyclic rate of fire on a machine gun. So there is no one right answer. Other than they were designed to fire at that rate.

[chupacabrachus]

Originally Posted by Cannibul

There are MANY things that determine the cyclic rate of fire on a machine gun. So there is no one right answer. Other than they were designed to fire at that rate.

Springs, speed of gases, length of certain parts, angles of parts that pivot or rotate, etc etc.

[einheit 13]

Originally Posted by chupacabrachus

Springs, speed of gases, length of certain parts, angles of parts that pivot or rotate, etc etc.

Weight of said parts plays a big factor. Look at an M3 'grease gun'...shoots fast pointed at 90* (3/9 o'clock), faster at 180*(6 o'clock), slower at 0* (12 o'clock). Some weapons have rate reducers to prolong barrel life. heat kills a barrel....design, open bolt fixed firing pin guns shoot faster than hammer fired guns.