You should be able to run up to 20 grains of Trail Boss in the '06, and still shouldn't break 1,500 fps.
I would start with 12-14 grains (70% of max case capacity), and work up to an accuracy load. The only applicable caveats: Do not compress Trail Boss. If you compress it and break the donuts, the burn rate becomes unpredictable (and faster).
However, your starting load velocity will be somewhere between 900 to 1,100 fps.
If you want something a little more along the lines of a reduced load, say 2,300-2,400 fps with a 165 gr bullet ...
I have a load I'm running with 165 gr Core-Lokts on top of 45.0 grains of IMR 4895. In LC 69 brass, it's running just under 2,400 fps, and has significantly less perceived recoil than full power stuff. But.. it's incredibly accurate in my rifle (even with factory-seconds Core-Lokts), and case-fill volume is still acceptable (75-80%).
I have a similar load running AA3100, which is about 91% fill in R-P brass. With 50 grains of AA3100, it's running about 2,300 fps with the same Core-Lokts.
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