I have now exceeded one thousand rounds through this cartridge, 680 through the beautiful GA Precision rifle, 260 through a new Winchester M-70 Ult. Shadow and at least 150 rounds through the original prototype M-70 that I hunted with in Alaska with Winchester. Talked to Mike Rock the other day and he said we might expect close to 5000 rounds of very good accuracy through these cartridge, particularly with his 5R barrels. My Rock barreled M-70 from GA is shooting very nice, seemed to take about 3-350 rounds to get it really performing. Took a while but now it cleans up very quickly, accuracy is sweet up to about 30 rounds and then it needs a cleaning. Nice cartridge, kills critters, I like it.