you just described the 6mm BR. It is a top 600 yard cartridge and holds its own most days at 1000 in the BR competitions and Fclass.
Bullets are half the cost, powder half the cost, and same barrel life with little better ballistics.
Go to www.savageshooters.com
and look for either new chambered or used 6mmbr barrel with 1-8 twist about 27-28" long. Several vendors stock new BR barrels.
Use Forester BR dies or you can go to BR central, look under the vendors for Harrels. They have custom 6BR FL size dies on the shelf. They just need a couple 2x fired rds to match the right die to your chamber, as they have numerous sizes.
Start with 105 AMAX (good BC, plastic tips so no pointing needed etc)
Varget or RL15 powder
CCI 450 primers
Lapua Brass (will last forever in the BR)