Flat base bullets are probably your best bet when shooting anything under 300 yds. there all I ever use. Boat tail bullet equal less drag at longer ranges which equals better long range accuracy. Boat tail bullets don't really come into the own till bullet speed drops below the speed of sound,above the speed of sound the nose of the bullet is more important.
Flat base bullets generally shoot better in old military surplus rifles like the two groove 303 British and M1903 Springfield because of how they distort the bullet,it leaves the bore in an oval shape and spins gyroscopically. A lot of the old 303 British rifles that used the old Mark 7 cordite ammo had there throats eroded very badly when the British switch to the Mark 8 ammo that used a BT bullet,the BT basically channeled the hot gases like a cutting torch and ate the rifles throats out. That's not the case today with modern smokeless powders and using BT bullets.