To 300 yards, probably a flat base bullet, but you'd need a lot of gun and shooter to measure the difference to the accuracy of a comparable boat tail.

All bets are off when the bullet drops from super sonic through trans sonic speeds.  Some bullets may do a little better than other, but as the sonic wave moves across the bullet, it going to pull the bullet out of sleep no mater what.



As for flat tail verse bullet tail, Bullet tail will have a higher coefficient number, so will retain it speed better down range than a flat base bullet.

Now where it really matters, and that is the amount that you can jump either type bullets to lands to begin with.  On a Boat tail bullet, it does not want to jump more than .008" to lands on ignition or it will pitch a bitch not wanting to hold a tight group.  On the other hand, flat tail bullets don't mind jumping to lands of even up to .080" and will group the same if they have a long or short jump to lands on ignition isntead.

So first figure out if you can keep the jump to lands short via long loading or not, and this will dictate what type bullet you want to use.  Hence long jump to lands with a BT bullet is going to be ugliy no mater how you look at it with bigger groups, and even with it holding its speed longer, which pushes the tran-sonic mark farther down range, your already off target to begin with as the bullet leaves the barrel to start with.

Brass prep, neck size only once you fire form the cases.
Note, if you don't want to do major brass prep to unify the cases in all ways, then use lapua brass.
I use LC match brass, but out of a 1K lot, only end up with about 600 cases that are unified to each other for match loads after prep and checks.

Power will be IMR 4064, primer Fed GM210M.  Neck size tension at .003", jump to lands at .003" as a constant.
Note, only load 100 rounds at a time, and once your shoot them up, double check your Ogive COAL to maintain the .003" jump to lands that the throat has slightly lengthen from plasma cutting of the 100 rounds, before reloading the cases for another 100 rounds.  If your going to get into a days worth of shooting that may be more than 100 rounds, then not a bad idea to take the other 100 round pack that you have pre-loaded that need to be fire formed to work back into the 100 cases if you have a problem with one of them.  I bring this up, since if I get a flier that I can't call as my own fault, that spent case gets trashed on the spot, and one of the other 100 cases that I may be working throught to fire form them, get put into play when it fire formed as part of the match 100 round ammo.  Hence any fire formed case from the back up pack that has been short already, stays in the pack until I needed it back in the match 100 pack.

Work the load's up off the bottom to find both your low and high nodes,  and as the season change from hot to cold, go find your nodes again for that temp your shooting in.

Bullets,
Sierra 168gr match HPBT for ranges up to 800 yards (round goes trans sonic around 900 yards depending on barrel lenght/ node speed, and again all bets are off when the bullet goes trans sonic and pull out of sleep). For out to 200 yards, use the low node since it will allow the bullet to sleep faster within the 100 yards.  300yards plus, use the faster high exit node since the bullet has the room to sleep before it gets to the target, and the increased speed will help to buck the winds better as well.

If you need to push past 800, to around 1200 yards before this round will go trans sonic with the high node load, changer over the sierra palma match 155grHPBT bullet  since you can keep it from going transonic before it gets to the 1200 yard mark.
Note, the Hornady match bullets are not bad, but will not hold as tight as groups as the sierra match bullets.

F class rig (trued with MAC 29" broach cut barrel), win 308 at 300 meters,  2-10 shot groups back to back (second 10 shot group on the left and can tell by the barrel fouling build up by the 2 round) using the 168gr bullet load at @ high node.

At 100 yards, rig will chew the same hole with low node so the bullet sleeps before it gets to target, since this is a .3Moa rig that will hold that for 20 round groups before the barrel needs to be cleaned again.