I dealt with the same thing. I picked up 50 primed cses at a gun show for the low price of $20.00. When I tried to load them I found out why they were so cheap, they were all LE cases.
I wasn't able to crimp them with my RCBS dies, although the folks at Hornady told me their dies will work. Shortening the dies will work, but the dies didn't belong to me so I didn't want to start grindng on them.
I bought a Lee Factory Crimp Die, as I was led to believe OAL wasn't an isse. It turned out I had to shorten the Lee die and although I can now load I'm not really happy with the crimp I'm getting. Fortunately I have a Handi so crimp isn't that big of a deal, but I felt it was pretty underhanded of the vendor to sell me the brass without warning me. Maybe he didn't know, but I doubt it. I think he sized and primed them only to be unable to load them.
I'll continue to use them until they're shot out, but I'll never make that mistake again.
GH1