Actually, drilling out the flash hole is necessary to prevent primer setback. Since these are low-pressure rounds, they're unlikely to fully expand in the chamber and push the case head firmly against the breech face. In those cases, the little pressure available can cause the primers to back out of the cases. There are few way more effective to truly "jam" a single action revolver than a primer that backs out...and since single action revolvers are traditionally the tools used to pop balloons in fast draw competition, this is pretty important.if you do make your own, you have to drill out the flash hole a bit to get all the powder to light.
I've actually seen some of the cowboy action blank shooters that will drill the pockets out enough to put a shotgun primer in with no powder and a wax bullet. Seems to have worked great for Bob Munden. Also makes them easier to load. Set primer and then push cases into a thick sheet of wax, bam done.if you do make your own, you have to drill out the flash hole a bit to get all the powder to light.