Originally Posted by a_sock
I understand that a greater velocity often yields poor accuracy, but have a question about controlling muzzle velocity with weight. Here's an example of what I mean. Gun A shoots 350 fps On .2 and is slightly more accurate than gun B, which shoots 450 on .2 . If gun B used .3 bbs to shoot the same fps, would there still be that difference in accuracy?
The inaccuracy seen from using a light weight in a hot gun is typically from the turbulence created around the BB at the higher velocities. A heavier weight in the same hot gun, however, would provide needed stability during BB flight due to its momentum during travel. Also, a heavier weight will be less inclined to be affected by crosswinds, which obviously will affect accuracy. So, to answer your question - yes, a 0.30 g BB would shoot with greater accuracy at the same base FPS. (To further clarify, I'm assuming that you are not performing a spring swap, so your 450 with 0.20 would likely translate to about 380-390 FPS with 0.3 g weights.)
However, weight isn't everything (just like velocity isn't everything). Other considerations includes the tightness of the inner barrel (less slop = greater accuracy), the quality of your airseal (less seal bleeding = greater velocity), and the type of hopup & bucking (to create the necessary backspin on the BB to counteract gravity and provide flight stability).