Flat.
Round.
It doesn't fucking matter, because none of us will ever be leaving the planet.
Go shill somewhere else.
Handgun: 9mm and/or .45
AR: Needs to be chambered in 5.56 so it can accept .223 as well.
Shotgun: Good to go.
SpouseAnon never picked up a gun in her life and was shooting Quarter-sized groups @ 100yds when her build was complete.
Stag Arms 5.56 upper and lower.
Full mass 5.56 bolt carrier group.
Yankee Hill 1:7 16in fluted barrel 5.56 + flash suppressor.
Spikes Tac buffer assembly w/ tungsten buffer.
Geissele trigger group.
Magpul furniture all the way around.
Trijicon ACOG w/ flash kill.
5 years and several thousand rounds later, she'll shoot almost bullet hole for bullet hole.