Re: Shooting a .223 at 600 yards
In 'normal' i.e. light to moderate conditions, it should work just fine.
I have a 12 F/TR in .223 Rem (surprise, surprise) that loves the B82BT seated 10 thou into the lands. Mid 2800s for MV, and very, very easy to shoot, both in terms of recoil and expense. The load will get to 1k... but thats what I have other guns more suited to the task for. The barrel has a 1-7" twist, and I did play with the 90VLDs some... just seemed like a whole lot more work (and headaches) for minimal returns, and not worth it for me at the time.
As to how well *can* it do... well... a couple years back I shot it at a four day match in British Columbia, 300, 400, 500 & 600 meters. Took 1st F/TR for the tournament, and finished 5th in the overall... and another guy shooting a .223 Rem (with S80MKs) was right on my tail the whole way.
After that, my plan *was* to just shoot the .223 Rem @ 600 & in, and shoot the .308 for long range. One thing led to another, and I'm currently waiting on a dedicated stock for the .223 (was swapping two barreled actions between one F/TR stock - not exactly ideal). As a result, the limited match time I have this year... will be with a .308, period. Once I get that stock in and bedded... I think the .223 will go back to being my 'fun' gun for local mid-range matches.
YMMV,
Monte