I have two 6X45mm's currently but have owned four in the past few years. Right now I have a DTech custom AR and a Cooper Bolt gun.
Here is the 6X45 AR. Normally it has a Suppressor on it but it broke and is being replaced under warranty.
Here is the Cooper
The 6X45mm is easy to load for and dies are actually very reasonably priced and it is as simple as running thru the die add primer/powder/bullet and go hunting. This cartridge was used by Bench Rest shooters back in the day is quite popular and I am surprised one of the big companies has not standardized it.
I have shot the smallest group I have ever fired with my old Bull Barreled AR using H335 and the 65gr VMax.