I found these primers In the reloading stuff I got from my father. I have memories of him reloading in the early 1950's so I'm not surprised he had some very old stuff. I have 9 or ten of these 100 round packs. I found reference to Winchester 3 W primers in a hand loading book by Mattern published in 1926. Ideal handbook #30 has them listed for 44 S&W, 45 colt and 45 ACP. Later #34 and #36 list them only which shotgun shells.
I wonder if these large primers are practical to use? Would they be safe from mercury. I read that early primers were made of mercury fulminate. I also have some 12 gauge brass shells that accept boxer primers. Is there a way to determine if they are non-corrosive? If they are corrosive what precautions are necessary? If any of you had them would you use them?