Shown on the site "big-ordnance.com is this 35x228 case used for a pressure test round. It shows a small square notch cut in the rim, and says there is a hole drilled in the case.
I have a uK made steel cased 27x145B Mauser round, with an identical notch, and hole 90mm up the case wall from the base. There is also a bare patch on the grey paint on the case where the propellant gas appears to have seeped out of the hole. Was this a pressure test round?
Having said this, I have heard of the concept of a pressure test with a hole in a case before, but what is actually being tested when this is done? The ammunition or the weapon?
My 27x145B case is fitted with a resin projectile, painted black with a red band. I thought this may be a replica, but is has the correct military lot numbers as if it was a real projectile of some sort. Is this projectile also something to do with pressure testing? The markinds are (just above driving band):G DM28 DM1315 LOT RG-50-1