The only Safari express rifle I know of is the Winchester mod.70

Only a gunsmith can work on that action.

It's not like the Savage actions.

I don't know of any repeater Savage action that can handle 3.6" cartridges.

338 Lapua Imp. would the be most cost effective compared to any of the Cheytac cartridges.

For Long range target shooting, I like the 338 Norma more than any other 338 caliber cartridge. It's very efficient and it's the right size for long heavy 338 bullets with out having to sit them deep into the case.