[260Ackley]

How important are square necks when reloading? I haven't had issues in the past with new brass, FL size to round the necks and load. I recently purchased some new 308 winchester brass and I'm use to some necks being out of round but most were pretty bad, and a vast majority were not square . I'm necking up to 358 so I'm losing some length already and would prefer to not trim but the necks aren't square. This isn't a bench or varmint gun, used for deer under 200yds. But I like my deer rifles to shoot no larger then 1 in groups at 100 yds. Do you think the squareness is an issue in this application?
If so I would loose more length and have to order in a new trimmer pilot.