Hi, I have a Remington 700 XCR Long Range Tac in 300 win mag Being its a .300 win mag I assume its a long action, I believe. I want to rechamber it to something bigger, but keep it in the 30 Cal, and willing to go wildcat ammo. However I dont want to replace the barrel. Was thinking something along the lines of 338 Lapua Necked down, .30-378 WBY Mag. How difficult is it to do this? Much modifications other than the rechambering of the barrel? Suggestions?