Originally Posted by Styrak
Very nice analysis. There's only one problem with it. You're using gas guns in which the FPS is affected less than an AEG. ex) Using heavier BB's does not translate to the same drop in fps as AEG's.
Barrel length factors in for AEGs. A short barrel AEG will behave that way, too.
Also, Don's original reason for posing the question was with respect to using GBBs in CQB/close range, and the safety claims that go along with that (and if using lighter ammo would be safer).
And there was an APS in there.
@Don: you could make some airsoft-caliber ballistics gel with some kitchen grade gelatin