[MiloXC3]

I know that about 430mm is the perfect length for Type-10 platform rifles.
Have a look into the barrel-suck myth if you haven't heard of it already.
The diameter of the barrel will affect the fps lots more than the barrel length though.

 

[MiloXC3]

Sorry Wyvernfirst, that's what I meant.

I think by help, he means 'will it perform better'.