Re: DPMS 300 SAUM Magazines ?
I have never seen a larger capacity magazine for the SAUM rifles either. To my knowledge, DPMS only offered the 4-rnd mags as the rifle was designed to be a hunting rifle and many (if not most) states have a capacity restriction for hunting rifles. As for finding some now...I highly doubt that there will be any aftermarket support for such a limited use/limited demand item...especially since DPMS has officially discontinued production of anything 300 SAUM. They don't even regularly stock parts for these rifles any longer (other than the interchangeable parts with the LR-308). They keep some stuff on hand, but you have to call in to find out if they have it or they can get it. If you can land some additional followers from the 4rnd mags, you may be able to modify a standard LR-308 20rnd mag to work, but I doubt it because of the swelling mag issue that FCS mentioned.