Spent the afternoon at the range testing out a new .308 mock-up with a heavier b

Spent the afternoon at the range testing out a new .308 mock-up with a heavier bullet. The 175-grain loads give a noticeably tighter grouping past 300 yards compared to my usual 150-grain rounds. Got me thinking about how important it is to tweak and test your loads, like fine-tuning a rifle for specific missions back in my USMC days. Anyone else see a big difference with your custom loads?