Fitch,sorry I thought I was talking to boilerup. But the angles on the K make the brass stronger and less likely to crunch when seating bullet. I'M SURE THE 221 IS BETTER BALLISTIC WISE BUT THE k IS A HOOT. @ 200 YRDS WITH a 40GR v-mAX THAt LOAD WILL FLIP THOSE PESKY VARMINTS A LONG WAYS, sorry...