Re: 300 ULTRA loads??
Lots of data posted already if you do a search for the powder, bullet, cartridge etc, etc.
I'm using 96gr RL25 and a 178gr A-Max at 3300 fps.
96gr RL25 with a 180 Scirocco, Nostler BT, Nosler BST at 3250 fps.
85gr RL25 with a 220 SMK at 2900 fps.
Pressure was a bit lower with the 178 A-Max so 3300 fps was attainable at under 65,000 psi on the Oehler 43. Accuracy was best with the A-Max also.
These loads were all max loads (65k psi) in my 26" barrel, so work up to them.