As you know a jump of 0.5mm or 20-thou is considered a reasonable minimum, unless you are wanting to push the bullet against the lands which some bench-resters do (and suffer for it if they are required to unload before firing).
In an AR I doubt if you will see any noticeable change in precision (group size) by shortening the OAL further than the max the mag will allow. There will be differences in pressure as you change the OAL and of course you will need to manage this. At mag length, guys are already experiencing quite long jumps so again, I cannot see making is shorter and therefore an even longer jump is helpful. Plus, shorter means less powder which again is unhelpful in an already 'slow' calibre. The exception here are short, fat bullets like the 95VMax which require a compromise between shank grip and jump. This is the one bullet I don't load to mag length. Everything else is mag length.
A bolt gun is of course different.
In an AR I doubt if you will see any noticeable change in precision (group size) by shortening the OAL further than the max the mag will allow. There will be differences in pressure as you change the OAL and of course you will need to manage this. At mag length, guys are already experiencing quite long jumps so again, I cannot see making is shorter and therefore an even longer jump is helpful. Plus, shorter means less powder which again is unhelpful in an already 'slow' calibre. The exception here are short, fat bullets like the 95VMax which require a compromise between shank grip and jump. This is the one bullet I don't load to mag length. Everything else is mag length.
A bolt gun is of course different.