The best way I've found to push squibs out of a barrel (esp. a rifle barrel) is with a widget I've built up that allows me to push grease from a grease gun down the barrel while held in a lathe. The grease "fitting" that goes into one end of the barrel is held in the tailstock, and the other end is held in the chuck with some copper wire wrapped around it.

Grease guns can generate enough pressure to push the squib out of the barrel. 

The single worst thing I've seen gun owners do is use a wooden dowel down the barrel and then smack it with a hammer. Usually, what happens is the dowel splits longitudinally, and then wedges itself in the bore. Getting that out is now a whole 'nuther level of "Grrrr" when I a job like that. Don't use a dowel to push a squib. Go get a piece of round brass stock that is nearly the diameter of the bore, and get some padded jaws in the vise.