Our pattern room doesn’t have all the different mags available for the SIG 300 caliber battle rifles but we have a few.
The first is an 8 round blank firing magazine, sold as the magazine also used for firing grenades. Items 2 through 6 are 7.5x55mm Swiss StG57 24 round magazines. These are also used in the semi-auto Pe.57, SG510-1, SG510-2, & SG510-6. They will also work in a SIG AMT or SG510-4 with little or no modification, since the 7.62x51mm round is only slightly smaller than the 7.5 Swiss. worth noting is that these magazines are machined and not stamped, folded, and welded sheet metal mags. You can actually see the machining marks on them.
Item 7 is an actual Swiss made .308 20 round magazine sold with the SIG AMT, it is identified by the circle manufacturer’s mark. Number 8 in this photo is a Chilean FAMAE made 7.62x51mm SG510-4 magazine. Aside from the mark it appears identical to the Swiss made AMT magazine.