I've been thinking about this a bit... I'd bet it's to allow some expansion to PREVENT a failure. It'll let the cartridge expand so the shoulder goes tight against the chamber and the base pushes tight against the bolt face.
That sounds right to me.Not belted. Belted is 7mm mag, 300 win mag, etc.
Engineered weak point maybe? Something to do with steel's expansion/ contraction rate being different from brass? That's where a case head separation would typically occur.
I've been thinking about this a bit... I'd bet it's to allow some expansion to PREVENT a failure. It'll let the cartridge expand so the shoulder goes tight against the chamber and the base pushes tight against the bolt face.
PM me your address and I'll send you one. Might be a week or two before I get a chance to shoot them, tho.I'd like to get my hands on a piece of fired brass.