Change your group mindset a little bit, consider shooting two shot groups, not three or five, however shoot three- five session ,two shot groups, I have had a lot of break action Optima Acuras Etc shoot 70 grains by weight and the I don't ask the little guns to put three - five in a hole I asked them to put two shots touching however, like I mentioned I shoot two shot groups on subsequent days. If I had all my shooting though that I needed to get done in one setting I understand the need to shoot groups with three to five I would make sure I let the gun cool off to absolutely the same temperature that it began with the first shot another reality is this almost everyone shooting the lightweight break actions if they're honest and they're shooting a group of three that third shot is going to roam off the group some unless they're really letting the rifle cool back to cold and sometimes fouling and in the stage of fouling plus ambient temperature same to affect things a little bit too I believe now of course from a hunting aspect it's those first two bullets I'm very interested in where they're going,,, it's why I'm so adamant about my Mantra, two bullets touching but only with break actions, anything else I expect the three- five shot group to determine accuracy.