I have a 6x45 AR in the works now.
Great caliber for Virginia's ".23 caliber or larger laws".
We did about 20 barrels (AR and R-700s) a few years back (my Smith has the reamer (it is Japanese market kinda thing)).
I did mine ultra light pencil as a trekking weapon... 5 pounds was the goal (came out 5 pounds 11 ounce bare)... I may still trim some ounce yet. Good enough shooter. TNTs are nasty little bullets.
If anyone needs the name of my Smith... drop me a PM.