Originally posted by Thurman
If the ball is in solid contact with the (flatline) barrel and not slipping (theoretical here) the maximum imparted spin should be on the order of 1500 rpm. The real number is undoubtedly lower, but that does represent more than an order of magnitude beyond the 26 rpm noted above.
Careful with the units there. I'm sure you mean 1500 and 26 rotations per second, not per minute.

Originally posted by Thurman
The egg/paintball analogy isn't very good BTW, the egg has a thin fluid (the white) surrounding a thicker fluid (the yolk). The yolk is suspended along the long axis by energy absobing elastic bands, which makes it hard to spin along the long axis. Try laying the egg on it's side and spinning it that way (go ahead and try it, I'll wait). You'll find that not only can you impart spin that way, but it sustains the spin nicely as well.
An egg is resistant to transients in rotational force. It is entirely possible to get a raw egg to spin on a table, particuarly if one applies a gradual increase in the force applied. As an interesting note, spin a raw egg and while it's spinning quickly stop it from spinning and then remove your hand immediately; the egg will resume spinning because of the decoupled nature of the white/yolk and the shell.

How does this apply to paintball? Not sure if it does. It is difficult to estimate whether the fill/shell of a paintball will be sufficiently decoupled at the rotational accelerations we're looking at. Going from zero to as much as 1500 rotations per second in only a few milliseconds is one heck of a transient force. In this regime, the shell/fill may well act like a raw egg does at lower transient levels.

I've got a couple of ancient (1980s vintage) paintballs sitting in a shot glass. The fill has completely separated in them and the shells are clear. I can spin them by hand and see that the fill remains coupled to the shell at the low end of the transient force scale; so at least at the low end of things a paintball does not behave like a raw egg.

BJJB