Re: .243 cal 55 gr Nosler BT Lead Free
At 4000FPS+ he's near max with Varget so 44+
I wouldn't worry to much about barrel life IMO. Once you break 1500+ rounds I've read and spoke to a couple guys that accuracy drops less than 1/4, 1/2" which for a want it dead yote gun that's not a lot of spread.
The other thing to consider is are you capable of shooting at maximum ability to even see the change in groups? And a few friends with .243s said they plan too change tubes at 2-3K rnds as the gun works fine for deer till then.
Besides a barrel replacement is a few hundred for a savage or a Rem700.