.22-204
We have built two .22-204s, one a rechamber on a well used long throated .223 m700 varmint with 1-12"twist. Accuracy is as good or better than the original chamber, a lot of .2"s, a few .1"s. I use Rl-10 for 40 gr. bullets, and Benchmark for 55gr. It is great on prairie dogs out to 600yd. Rem. brass works well, no primer pocket problems. Simple neckup to 6mm, then down to .22 for a tight fit,(headspace).
The second one is a new Bartlein 1-8" on a 722 action, not much time on this one yet, but put in all the W-760 the case will hold behind a 75 grain AMAX, it will leave a .223 behind easily! Reamer came from Manson. kjk