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Folks winning matches and setting records at the longer ranges seat bullets used for single round loading a bit long so they set back a few thousandths when chambered. Then work up a load that shoots the most accurate. It's usually the same load their previous barrel chambered for the same round used. This helps the bullet align a bit more perfectly with the bore when it's fired. And it seems to correct somewhat for bullets that are a bit crooked in the case, too. Bullet runout can be as much as 1% of the caliber (.003" for 30 caliber, .002" for 22 caliber) and excellent accuracy happens.
If the ammo has to feed reliably from a magazine, then whatever the longest OAL lets that happen does just fine. But ammo's got to have pretty straight necks and bullets to do well accuracy wise when seated back off the rifling; the more they have to jump to the lands the straighter they have to be.
Note that if you don't shoot at least 20 shots per test group checking this out, you may get the wrong answer. Most any jump distance can yield the smallest group with 5 or less shots each are fired.
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