Interesting. I went down and checked my reamer and dies. my chamber was cut by Hart barrels with my ptg reamer labeled 243 ackley imp. My redding dies are marked 243 win imp 40° and work perfectly. I have the bushing fl sizer and competition seater, bot marked alike. I dont have any brass on hand as it was repurposed. Ive never heard of a different version with a 40° shoulder.