Gunsmithing What .30 cal cartridge for Stiller Tac 408 action?

[wadcutter]

I have a Stiller Tac 408 single shot action and I want to make use of it for long range competition work.
The bolt face is made to take standard 0.640" size cartridges such as the Cheytac range.
I have reason to chamber this action with a .30 cal barrel and would like advice on a suitable cartridge. Thinking maybe a shortened Cheytac case so as to not burn out the barrel too fast.
Thinking sort of like a 6mmBRX on steroids shooting the heaviest .30 cal pills at 3000fps out of a stiff 30" barrel.
Rifle will be used for 1500 yard matches, maybe three times a year with 60 to 80 shots per match.
Must be a .30 cal. Calibres over 8mm not permitted in the competition. Any thoughts or options.

 

[excaliber]

Shorten the Cheytac case to 2" and capacity will be close to the 300 Lapua. It will burn more efficiently so you should get more velocity per grain of powder.

 

[wadcutter]

That's sort of what I had in mind.
I have been looking for any existing cartridges but can't seem to find any based on this case head size.
Looks like I will have to get a chamber reamer and die reamer set made.
Brass will be easy enough as Bertram brass is made just down the road from me and I can get some partly formed 408 cases to play with.

Another option could be to get a second bolt made up with a standard magnum blot face? I will contact Stiller and see if they would do that for me.

Should be interesting!