I shoot many different berger bullets but nothing in the 300 short mag. I have found that in all but one of my guns shoots best when I seat the bullets .005 into the lands and grooves. I have also found that loading and load development with these bullets requires alot of patience. Also, try grouping at farther distances like 200 or 300 yards, some say that these bullets might not stabilize and group good at 100 but out at farther distances they will group very well. I have not personally experienced this with any of my guns, but there are many that have. Keep trying and make sure that you do everything right before you get to the range. If neck tensions are different, that could cause inconsistancies, if you get sloppy with the powder, that might play a role. All in all if you do your part and make sure things are as close to perfect before you shoot then it narrows the possibilities down. Just keep trying and have patience because when you find a load that works it will be worth all the trouble that you had to go through. Just my opinion though.