That's an unfired .30 Remington round.
The fired brass from my .30 Remington Model 8 rifle looks a lot closer to the .30-30 Winchester's.
And Remington's reason for the round was to duplicate the .30 WCF/.30-30 Winchester's ballistics in an autoloading/pump rifle. So case capacity was the biggest factor. The shoulder design was probably tweaked to enhance feeding from the box magazine of the Browning-designed Model 8, just like the removal of the rim.
On a side note, I'm working with the Lapua and Lost River Ballistics 6.5mm offerings on my larger 6.5mm rifles. I've got to get busy on my 6.5 SPC/.26 Remington AR-15 project - .277, indeed!
Not that similar, then - the shoulder angle is quite different.
The fired brass from my .30 Remington Model 8 rifle looks a lot closer to the .30-30 Winchester's.
And Remington's reason for the round was to duplicate the .30 WCF/.30-30 Winchester's ballistics in an autoloading/pump rifle. So case capacity was the biggest factor. The shoulder design was probably tweaked to enhance feeding from the box magazine of the Browning-designed Model 8, just like the removal of the rim.
On a side note, I'm working with the Lapua and Lost River Ballistics 6.5mm offerings on my larger 6.5mm rifles. I've got to get busy on my 6.5 SPC/.26 Remington AR-15 project - .277, indeed!