I have found the same recently when at the range. Just grabbing bullets out of my box, and my groups started to open up with the 250g shockwaves - when last year I could fit 3 shots into a half dollar! Upon inspection I noticed that I had two different types of sabots with the shockwaves. I had bought 60 (couldn't pass up the deal) shockwaves online since I was running low- and had to order the harvester sabots (.452) from Cabelas in order to regain some consistency in my grouping. The best grouping came from the sabots packaged with the shockwaves from last year; but, I am still holding 2" groups with the harvesters at 100yds.