Buddy of mine came by a couple days ago after a trip to the range. As usual, he grabs whatever loose brass that's laying around for me use. He scored big for me this go around, and brought by tons off brass including around 200-250 of .223 rem. So this evening, I decided to punch out 100 rounds. Every thing going smooth for the first few until I spot a case with a short shoulder. At first I just pitch it in the "junk brass" bucket and go on, then another, then another then another, and whoa....whats going on here..... So I meticulously dig through them all and low and behold there are exactly 20 rounds of this brass that just aint normal. The overall length is .025" shorter, and the shoulder is at a more flat angle than typical. Probably around 18 degrees. Neck length is normal. Below is a pic of one of these "odd balls" next to a typical. Both are clearly stamp F C 223 REM. Any thoughts?