Small or Large bolt pattern?

Most of those aluminum slot-mags had the basic size cast on the inside surface somewhere.
There is another way to measure the bolt circle, but you need a caliper.And it's kinda complicated. you measure the diameters of the holes and add them together. Then divide that number by two.To that result you add the distance between the holes. Next you double that. And finally, you round the result to the nearest 1/4 inch. I told you it was complicated..........
I love slot-mags. To me they are the epitome of the period. Well, except for those ultra rare KHers. Those were killer looking.Well ok, not killer, but sweet!as the kids say.