This is that 6.5x300 mark 5 weatherby
Looks like a very appropriate barrel length for a Weatherby mag too
As an aside, - i have been talking to a couple of 'smiths about assembling a long range rifle for me based on a Vanguard/Howa action in .300 Weatherby and i recall a guy trying to steer me towards a Creedmoor - stating
"You know, with those big overbore magnums - your barrel life is really going to be compromised - you might not get but 1500-2000 rounds out of it !"
---- i just politely acknowledged his statement and thanked him for the information and giving me something to ponder - but walked away thinking
"How many rounds of .300 Weatherby does the guy think im going to be shooting" -- theres a ton of these rifles out there that are decades old and probably havent seen even a hundred rounds in their lifetime. If he had stated it would be a 250 round barrel , that might give me a little bit of pause , but 1500 is absolutely not a factor