I hope you won't mind if I jump in on this subject for a moment.
I'm sure that Jim was hoping to save money by getting just a couple of slugs for each caliber.
I got a 45 caliber slug package (20 slugs) and used it on 3 revolvers.
I used several slugs each. If you haven't used them before you'll probably use a couple more than you think when you realize all the different places in your gun that you want to get a specific measurement from.
If you push the slug all-the-way-through you'll only know the diameter of the tightest place. That is probably good enough for most do-it-yourselfers but it drove me nutz!
So I made a set of short dowel pieces that I could push in from the cylinder-window [the breach of the barrel] of a revolver (one after the other) until I could push the slug back out from where it was.
BTW,This works for the lever-gunz too.
That way I could find and measure all the tight spots in all my gunz. (There were more than I'd believe without slugging! "Horrifying" is my favorite descriptive term for it.)
Then there was the matter of the chamber throats of the cylinders; mine were all very small, different from one-another but slightly bigger than the bore which took a few of the slugs to sort out. (Rugers, ya gotta love 'em.)
The fact is that if what you're doing is gearing up to fire-lap the gun, you're going to shoot lapping-bullets through until the barrel is smooth all-the-way-through anyway.
If your cylinder throats are like mine were, you'll want to hone those throats to the correct diameter as a last operation if at all.
I guess I'm really just being long-winded in agreeing with Veral, you'll be glad you have many slugs for each caliber/revolver and 3 or 4 for the single-shot gunz is useful too.
As time goes by you'll probably be very glad you have a couple or few left for each caliber you buy.
I occasionally let a friend push one through his barrel to prove to him that his barrel is NOT free of tooling marks and other assorted "snags". Doing that sometimes turns a care-free shooter into a "jacketed bullets only" shooter for awhile.
They eventually come back into the fold and become one of the faithful when the cost of jacketed bullets wears on them for awhile.