Colin and Glenn,
This sounds similar to using high velocity ammo.
Very god and 50 yards but between there and 100 the bullet upsets when it breaks through the sound barrier.
I am waiting for someone to tel us what ammo they were using and a complete assessment of 10 shot groups from 5 or 10 varieties on ammunition.
One 5-shot group does not spell accuracy; 5 10-shot groups do!
Right on. This is it. Often 60-70% of a 10-20 rnd group of crappy ammo like CCISV looks great. It’s more likely that 5 good ones coincidentally end up in the same group than 10 or 20.