Wear ear and eye protection, keep them away from powder, and decap them very slowly. They can occasionally go off doing this, and are surprisingly loud. As long as the primers weren't crimped, they mostly come out intact. Watch for anvils that fall out and so on. I wouldn't use them at the National Matches, but for plinking or non-precise comparisons, they will likely be OK. Modern priming mix is slightly flexible. The brittle and easily cracked stuff isn't something you see anymore. At least, not in domestic brands.
As Straight Shooter just mentioned, they may be loose in some brass.
