Two years ago, I had something like that happen with 2 boxes of federal 243 ammo. I bought the ammo for a friend who called me up during the first week of deer season and told me the bolt wouldn't close when trying to put a round in the chamber. I went to the farm to look at the gun to see what the issue might be. The gun was clean, and I didn't see any damage or obstruction to the chamber or damage to the bolt. In a conversation with him he told me he had 3 shells from last year which he used to shoot but after that this problem arose.
I took a shell out of the new box I gave him and none of them went into the chamber correctly and just didn't seat properly, so you couldn't close the bolt. I checked all the shells in the 2nd box and every shell in that box had the same issue. Both boxes of shells came from the same lot or batch number. I bought another box of 243 shells I had for some time with a different lot number and they all worked properly.
I called federal and explained the issue and asked for an even exchange which they refused, stating they would send me a check for what I paid for the shells after they examine the shells and determined what the issue was.
Within 3 or 4 weeks I received a check but no explanation as to the cause. Being curious by nature I called them to see what may have caused the issue. I was told that information was proprietary, and they would not share that information with me.
