I'd try a 100 grain Nosler Partition and do my best to place it in the middle of the deer behind the shoulder, hoping to take out both lungs. I'm old school, don't know too much about any of the newer bullet designs, I'm sure someone will have a better answer.
I have killed 8 deer with Nosler ballistic tips, at 329 ~ 510 yards.
The bullet looses allot of velocity by the time it gets way out there.
Still, the bullet makes a big exit hole after going through two lungs.
That bullet is on the fast expanding extreme end of deer hunting.
I hunt with guys that use partition bullets for deer hunting. I consider that the extreme end of slow expanding for deer.
You pay your money and take your choice, there is no consensus on what bullet for deer.
I have used the 105 Berger VLD out of a dasher out to 500+, but that is a 1-8 twist, 30 inch tube. I think you need to stay under 95g with your twist. I do know that the 105 at around 3050fps is still cookin along pretty good at 4-500 yards.
I'm loading up some 95gn Nosler Ballistic Tips at this very moment. Thought I'd bring the Win 70 HVB in .243 Win. along for S & G (still taking my 700P in 7mRM). I found a great load about two weeks ago; 44.0gn of Viht N560/CCI BR2's and prepped/annealed RP brass. It's running 3114fps and printing in the .2's which is definately good enough for deer.
I took a groundhog about a month ago with this load at 580yds, he never heard the rifle go off! This load is a half a grain under max in Nosler #6 so it should be safe in most modern rifles. Good luck. JohnnyK.
95s to 100s, like others have said. Different rifles like different loads. Try a few and see what your rig really likes. Keep a data book and make judgement for yourself. I know you were wanting a clear cut answer, but often, each particular rifle likes something distinct. Wish it was that easy. Good luck.
I used a Hornady 100gr .243 BTSP on two deer this fall with Excelent results. at 100 YDS .7 inch groups at 300 YDS 2.15 inch groups. Also just FYI on antelope my son used the same rifle with Sierra 85gr. HPBT Gameking and DRT Antelope doe at just under 400 yds clean through lung shot & was as fast a kill as I have seen with any rifle or CAL.