... picture it, Sicily. 1942...

So I thought I had all the stuff I needed for the various calibers I have to reload; brass, bullets, powder and primers.
I started showing my daughter how to reload and even let her have a go on some 9mm brass. Showed her how to lube the cases, how the single stage handled with both lines and unlubed cases and so on. I went to show her how to use my Lee hand priming tool and... discovered I don’t have the shell holders for two of my calibers...

Now for the dumb question. Aside from going online and waiting for the mail or venturing into a store and risking catching the crud... is there any way to still plug a primer in to a 9 or even 223 case without their prospective shell holders?

Well, you could try putting the case upside down in a vise.  Don't squeeze too hard or it will crush the case or deform the rim.  Place the primer in place and gently whack it with a hammer.  That should push it into place and seat it.

Please don't do that!

Have you tried another shell holder for fit?  Sometimes they will be a little loose but would hold it well enough to work.  Just be gentle with the priming so you don't force it out of the shell holder and mess up the rim.

Set the primer on a hard, flat surface. Set the case on top of the primer. Drop a rod down into the case mouth and tap the case down over the primer.