A friends 338 with 29" 1-9 Bartlein managed 2850 (+/-) from a 300smk over 94.5gr Retumbo loaded to CIP length.
My TRG42 (26.5"??) gets 2675 from a 300smk over 90.5gr Retumbo at max magazine length.
Some barrels are faster than others, but I suspect 2900+ is going to be a tough number to reach from a 29-30" pipe with 300s magazine fed.
If you hang the bullet way out there and single load them, I suspect 2900+ will be a lot more likely.