Bore size of Viewloader VL barrel?

[BigDave]

I got one of these but have no clue what the bore size is. Shooting Proballs (yea they suck, but they were free) they were shooting trrible and a few got stuck in the barrel. I assume it is either small bore or the paint was just that bad. Anybody have any info on this?

[Ramstang]

Shoot smaller bore paint like Marbs or swirls or Dusk. I shot PMI premiums through mine and they got stuck half way and broke lots.

[josh_hill]

It is a med-small bore barrel. Super swirls work well in it.