Shellholders for the belted mags are the right diameter, but I am not sure about thickness. I keep a Quinetics Universal on my bench for stuff like this. Lacking one, I would have at a spare shellholder with a Dremel tool and a fiberglass cutoff wheel reduced to just less than rim diameter.
A forum community dedicated to the great outdoors and hunting enthusiasts. Come join the discussion about hunting, fishing, survival, archery gunsmithing, optics, reviews, accessories, classifieds, and more!