from my .177 R9, however they were looser fitting than I liked so I ordered 8 tins of Exacts labelled 4.52mm. In the past I reported my bad experience with the supposedly 4.52mm tins where I even had two dry fires at a field target match with the R9 and would have had a third if I didn't see the pellet flipping out of my leade when re-latching the barrel.
That episode started marathon pellet head measuring sessions which ended up with a few thousand supposedly 4.52mm pellets being measured....
Some actually measured 4.52mm but most measured 4.50/4.51mm with the second most pellets measuring 4.49mm. LOL....after all the measuring I wondered why JSB even listed supposed head size on the tins!
Thinking that perhaps my "measuring technique" was questionable I measured a bunch of Air Arms domes labelled 4.52mm and I had a much higher percentage of pellets actually measuring 4.52mm so my measuring technique was indeed verified to my satisfaction.