ORIGINAL: SwampCollie

There are several reasons why this maybe:

First, I notice you live in Missouri, which is generally flat, but.... is there a large frequency of rocks in the soil in your area? Hilly at all?

Secondly, depending on how many birds you have killed, you may very well just be killing 2 year old birds with steady consistancy. Jakes and 2 y.o birds do not have sharp spurs yet, they are rounded off considerably.

Thirdly, there is a chance that you just haven't killed a bird with NEEDLE sharp spurs yet. Not all spurs are super super sharp, though the spurs of a 3 year old bird are noticeably sharper than a 2 year old (generally). When rocks come into play, all bets are off. I've killed birds with needle sharp 1" spurs, and birds with relatively dull 1 3/8ths spurs. My best set of matching 1 5/8" spurs though are both very sharp on the points.

Just a few suggestions. Could be one of these or something else.