Sorry Guy, I'll try to include a Donut, next time! LOL!!!
Yes, it's an Investment Cast copy, of a Farquarson (Google - Gibbs Farquarson).
The Aussie manufacturer, made up several hundred (?) of these, for the custom rifle market!
The owner of this one, has a few more of them that he wants to have built up.
Yes the .600 NE is BIG and would deck Skippy's real well but the .22-250, would be a better choice for this!
My personal favorite Skippy rifle, is a old Tikka, LSA 55 in .222, and I have shot 2,000+ Skippy's with this rifle alone!
The situation with using anything bigger than a .222 or .223 (in the area where I live), comes down to economics.
So it doesn't take many years to shoot out a barrel, when using any larger powder capacity cartridge, when your shooting up to 50 each outing.
We shoot so many of them (and 99.9% are Head Shots (Brain Shots), whilst spot lighting from a vehicle at night!
Most spot lighting shots are inside 150 meters/yards, and after 50 shots, some barrels can be a bit fouled and the rifle starts to get a bit less accurate!
Spot lighting is the main legally authorised method (along with Caliber and Bullet weight, 50grn .224" bullet, at 3,000+ fps) we have available to us these days, and it can be very effective means of deckin Skippy's!!!
I bet a 6x45, 6x204 Ruger, or 6TCU would be good rounds for barrel life and offer a bigger pill. It may not be needed but I bet you'd get 4000 to 5000 rounds of barrel life from them. They would cost you a bit more in bullets but they may go longer before fouling becomes a issue.
IdahoCTD, sorry for the delay in replying, been a bit side tracked with stuff.
Yes mate good advice, those 6mm cartridges would be chooses for deckin Skippy's!
And a bit better at dealing with wind etc as well.
A couple of Pro-Roo Shooters I know, used 6mm PPC and 6mm BR for some time, and were very happy with their use!