Go for it. A 7mm 140g will get the job done quite a ways out there. I us one in my 7mm RM at 3214fps and had one exit on a broadside at 400 yards. North Fork HP instead of Barnes TTSX but the TTSX are even harder to stop.
At 600 yards and 7000 feet, your TTSX load should maintain over 1500fpe and 2200fps.
FWIW, IMR 7828SSC gives me 3358fps with the 140g TTSX with my 7mm RM. I use TTSX and LRX in several of my rifles and will likely do so in the 7mm RM when I run out of North Fork.
Coyote Hunter - NRA Patriot Life, NRA Whittington Center Life, GOA, DAD - and I VOTE!
No, I'm not a Ruger bigot - just an unabashed fan of their revolvers, M77's and #1's.
A good .30-06 is a 99% solution.
| 
