Mr Cannoli.
Thank you for the definition of a squb.
A squib is a powder charge that is so small that the ball only goes partway down the barrel.
You would treat it the same as no powder charge at all.
Importantly, if, somehow, you knew that you created a squib it would be easier to insert more powder in back of the squib via the touch hole on a flintlock or the hole in the nipple holding snail on a percussion rifle.
More important, once you have inserted the powder you should be sure to now reseat the wandering patched ball back down on the powder before firing the former squib down range.
Under no circumstances should you ever fire a rifle without having the ball nicely seated on the powder charge whatever its size might be. Because that is how we can create an interior bulge in our now quite useless gun barrel.
If its actually a squid in your rifle barrel you have gotten your sports confused.
Dutch