Originally Posted by robbobsam
90% of the time this rifle will be used for long range varmint shooting out to 600yds and beyond. In addition I may use this rifle for a bit of target shooting maybe out to 800yds.
If I were you then I'd look very seriously at 6.5 creedmore, 6.5 Lapua, and .260 Rem. Far superior rounds for those purposes and it won't cost you a dime more on your build.
The .223 bullets simply cannot compete with the above for this application.
The only .223 I'd consider even adequate would be a .22-250 or .220 swift but even at the higher velocities they provide you are still hamstrung by the limits of the ballistic coefficients of the .223 vs the above.
There are however a hell of a lot of guys still addicted to the .243/6mm for your applications as well.
I just prefer the 6.5's because, again, higher bc's and much better performance in wind/long range.
I've done some shooting (successfully) at ridiculously long ranges with both the .204 Ruger and .220 Swift, but I know full well I am much more limited with them than I am my .260 and if I want to shoot a deer or even larger game with the .260 as well as varmints, I'm not under gunned.
Since you're still working on this project from the ground up give it a good long think before committing since your original deal fell through. Consider it now an opportunity rather than a problem.