Originally Posted by mcguyver
Sorry, there is nothing incorrect in what I said.
Explain please why my M16A3 PTW will shoot 0.25g BB at 497 fps but will shoot a .20g at 530 fps? 20% decrease in BB mass but only a 6.6% increase in velocity? Don't worry, I already know the answer.
My old Marui G3 shot 265 with 0.25g and 295 with .20g. Same BBs (I haven't changed brands in years). Same 20% decrease in mass, but now an 11% increase in velocity.
Not all guns are consistant, and you can't say across the board that an X change in weight = a set velocity change.
Different barrel lengths and how your hopup contacts the BB also affect it. If you have a gun with the same barrel and same length and same/similar hopup you'll get most likely get very close to the same results. 30 FPS going from .20 to .25 seems right. That's what I got with my AUG with stock TM barrel. Notice both your guns changed by 30 FPS.
Also, BB mass % won't = velocity %.
And gas guns are a whole different deal too.