I've seen this for cat sneeze loads, usually with no powder - but I've not seen any that appeared factory like that.

Just a guess - perhaps they were crimped berdan originally and that large area, when opened up for a 209, appeared factory? Dunno.

I've got some .223 brass so altered for use with air rifle pellets. It works for that application. A purpose ground drill bit is all you need to convert cases. I am not aware of such commercially available projectiles for the .30 although I think there were some in the past. They might still be available. That system, the name of which escapes me at the moment, used machined cases that utilized .22 RF nail shooting cartridges to provide the propulsive force in whichever form they were made.

--
Sincerely,

Hobie

...but I was never sure what caliber it was (didn't try real hard to find out). I don't think it's a true shotshell primer. If I remember later ill look.

nm