Well, I got to the range today. I must say, my groups look a lot like yours, only mine were shot at half the distance.
But the similarity lies in some nice groups then a wild flyer and then some spread out groups, plus the moving around the POI. I was wondering what could be going on with my guns so I looked down the bore of my 510 and it looks terrible. It has what looks like greasy patches which made me wonder whether those odd flyers out of a seemingly tight group, could be the proverbial purge flyers?
The other oddity I found was a nice centered group followed by an attempt to 'prove' that group. The first shot goes to the center then the range gets closed. On resuming, the next shot of that group goes wild but then the rest fall back into the POI. Barrel and greasy lube cooled down resulting in a purge flyer maybe? I'm just wondering about it.
The guy shooting next to me with his CZ target rifle was shooting flies off his targets at will. No flyers (excuse the pun). He literally put ten shots into one hole - not a group - a hole. But then he was shooting 'cheap' SK Target ammo at NZ$15 a box. I couldn't find any when I looked. Ordinary CCI sub-sonic HP ammo costs NZ13 a box, just for comparison.