The size of the group is more dependant on the quality of the testing, ie, the rig and the tester, than the pellet (within reason and some real rubbish pellets excepted).
Accurate testing is not easy and needs some very sohisticated eqipment to both hold the gun and measure the group to get accurate, consitant and representative results, I've seen testing at Steyr, Walther and MEC, and seen my wifes modern rifle tested at MEC and shoot a perfect 10 shot 4.50mm hole (can't call it a group) .
I was amazed at Steyr to see all diferent match pellets being used for testing with almost identical results, I thought that's good, they are testing to cover all pellets, the real answer why? They said "We just buy what ever the local shop has in stock!"
For classics the meisterklugeln is what it was weened on, no choice on weight or size, but at top world level for modern guns there are only two makes RWS R10's and Qiuang Yuan.
Have Fun and Good shooting.
Walther KK500 Alutec expert special - Barnard .223 "wilde" in a Walther KK500 Alutec stock, mmm...tasty!! - Keppeler 6 mmBR with Walther grip and wood! I may be a Walther-phile?