R1 Magazines. The magazines for the R1 Big Game rifle are available in multiple calibers and capacities. These OEM magazines are available in calibers like .223 Rem, .30-06 Springfield, .300 Win Mag, .308 Win, .338 Win Mag & more. Made from steel with a durable black polymer base, these magazines are sure to last a lifetime. Benelli R1 .30-06 10rd Magazine 81123