Back when I shot Hunters Pistol the common thought was that you got better accuracy from Once-fired brass than you did from “New” brass.
I don’t know if this was just local thinking or there is any truth to it. After all .22lr is always “new” and obviously accurate.
So, do I need to shoot my 30-30 brass at least once to make it accurate, or would it be just as good if I shot “new” brass?

Thanks,
Michael

The Army Marksmanship Unit has done studies where they say new brass provides the best accuracy. But, from what I remember there was not a lot of difference between new and fired brass. FWIW, the Army teams supposedly only use new brass when they shoot matches----Across the Course matches and long range matches--they fire it and leave it. I know from my personal experience I have had some really nice unexpected results when I fire form new brass.
As bad as my offhand hold is, I think I get some benefit from the shot not going where I point it...HA! So I don't worry about it.

Difference of eenie and meenie. Shoot what ya got.

Also keep in mind that the AMU usage is different than other shooters' usage. Their particular usage is for multiple different pistols and rifles that are primarily auto-loaders that eject the ammo onto the ground, risking variance in expansion and damage due to that. That is a very different scenario than a single shooter using all brass through a single rifle who doesn't let the brass bounce off of whatever may be in the ejection path.

A better source of relevant data for this would be what benchrest champions use. From that data set, you can start removing steps in their process that don't provide enough benefit to be worth using in standing matches at known distances, which are shot at relatively large targets in the cowboy matches.

For a 30-30 with open sights, you are not going to see (no pun intended, LOL) a difference.

"New" 22lr has enormously different levels of 'accurate'.