Desert tech or other?

#1
I am having a difficult time deciding what rifle to purchase in the next 6 months or so. I already have a Leupold MK 5HD 5-25 tremor 3 and an ADM 40 MOA mount.
The rifles in question:
1. Desert Tech HTI in 408 Cheytac
2. Cadex defense in 408 Cheytac
3. Custom 408 Cheytac using a XLR Chassis with most likely a Stiller tac408 action.
Use, I will not be competing in any competitions, this will most likely be a toy that slings 419 grain projectiles at steel.

Any insight or personal experience with the above will be greatly appreciated.