Magazine maker info, looks like Sig originals....
Got ahold of my brother tonight. He reports that the mags are two stainless, one blued. All three of the cracked ones have the dovetailed rear seam and Sig-Sauer on the left side, near the bottom. Also present is a small circle with a triangle in it, a curved line extending out from the points, bottom rear of the mag. The damage is at the *back* of the magazine, not on the feed lips but on the area that roughly matches with where the rear of the topmost cartridge sits against the rear of the mag, just below the top of the magazine. He said there is sort of a dent there on the body of the mags, almost like the slide going forward somehow hits the rear of the magazine. We are assuming that these are Sig originals, about two and one half years old. He has three other mags marked "Made in Italy" on the right front side vertically arranged. No dovetail rear seam. The have no cracks and I'm assuming they are Mec-Gar. He will start in with Sig to get replacements next Monday. The salesman at the store said Sig would replace them, no questions asked, with about a four week turnaround. He will keep track of when and how it works out and I'll post a new post then.