Ok I just got back to the range yesterday and have some updated velocity numbers.

I decided to push the 165 SGK to the 2600 level. Sierra book max is 43.1 gr RL-15 @ 2700 FPS with a 26" bbl test rifle. Since I was pushing Hornady 165 SSTs @ 2600 w/43.5gr RL-15 (Hornady book max 44.3, Speer 47 gr for 165) without issue it seemed safe to ladder higher. Below are the Chrono Results:

COAL 2.75 (mag length) 85 deg, 5250 altitude

1) Sierra GK 165, 43.8gr RL-15, 2628 fps avg, 2638 hi, 2589 lo
2) Hornady SST 165, 43.6gr RL-15, 2657 fps, 2663 hi, 2638 lo

Interesting that I only loaded .1 grain higher for the hornadys, but got 57 fps faster velocity. Since the highest velocity I got last time at 44 gr RL-15 was 2639 fps average. I stopped at 44 because I got a slightly flattened primer.

In conclusion, my hand loads are coming in at or close to book velocities with a 18" barrel vs 22" test barrel for the Hornady, and 26" test barrel for the Sierra. Both of which are conservative loads vs. the Speer book at 47gr (compressed) @2812 fps.

If not for the flattened primers (every other at 44), I would have taken the Hornadys at least to the book max to see if I got closer to 2700 fps.