What is your opinion or maybe solid info of what causes the pesky flyers that ruin an other wise great grouping. I resently shot 50 rounds from my .41 magnum rifle and many times out of 5 shots thre went through the same hole and then here came a couple 1 inch flyers. Same powder, bullet seating, cases, primers, bullets and all weighed on a calibrated electronic scale!

Seperate out the cases that throw the fliers. Retest your groups with the "good" ones, than try the "bad" ones on a seperate target.
I'm thinking about a internal volume issue here.

I see the cases may have different volumes causing the differance. Also I read where weighing the cases might help. I guess running a cc volume on each case would do. But will seperate the ones fliers came from. Thanks

Welcome to the forum Blob 1.
What kind of rifle you shooting?

Right now I am tuning my Marlin .41 magnum rifle in. Then comes the Ruger .260 and then the old 7.7 Jap sniper rifle. I sold sll my bull barrled rifles, .243, .223, .308 and my 30/06. Bought a new ss Ruger MK 77 in the .260 caliber to hunt with. Will use the .41 for some thickets and wild hogs and haveing fun with the Jap shiper rifle!