The rifle he uses for his long range shot is a Ross Sporter, I'd presume a 1910 Model,,looks like it anyway.
I've never seen a TD model of one but the Brits would build about anything for you.
The 'scope looks like a Winchester A5. Those are about the same 1910 period and forward I think.
Mounted backwards on Clints rifle I believe but maybe he shoots better with it that way. Clint knows his limitations,,,
.280 Ross caliber,,the open sites(s) on the Sporter have only one leaf ,,,marked '0 to 500 yrds'.
Pretty flat shooter.
Clint only needed to put the bead on the guys hat to bust him in the chest at the 800yds or so I'd think.
Once I get mine shooting I'll try that shot out on paper!