I think you’re too hot, try backing it down to 3200 fps in a 22” with the 108 or 109. I would also jump them .050 to .060”. N565 has given me the best results in my 6prc’s.
The 6um wouldn’t be totally complete without a heavy TMK. My guess is it has to be coming. Just a guess.
Sierra seems pretty good about making bullets if you order enough.
It takes about 1 to 1.5 seconds to chamber a round. I have never had a missed opportunity due to having an empty chamber on a rifle. Condition 3 for me.