I purchased some .22 Rimfire ammo several years ago, probably about 5, and when I went to the range a few days ago, over half of the ammo would not fire. I tried it in 2 firearms with the same results. Both firearms made nice indentations in the rim of the ammo. I tried rotating the ammo so the pin would strike another part of the rim and a few of the rounds did fire. This is not a cheap brand. The ammo is a high grade from a name brand. What gives?