First make sure you have the right designation.
AR10A (the newest release) is called A because the so called DPMS/SR25/Pmag system is from the original AR10 waffle magazine design. This is the style DPMS, KAC, LMT etc etc use and is considered to have won the mag standard choice.
AR10B (the older more common version) uses M14 based mags. Think B stands for ban as the assault rifle ban in the US was the reason for Armalite going to this mag over their previous one. They wanted a reliable mag that was available in vast quantities pre ban. M14 mag it was. Although the Gen 2 AR10 mags are pretty nice.
So for the AR10B, Wolverine has them. Or get them imported, used etc. I usually wait for when they are on sale.