Did this a couple years back in my 6xc, RL16 has good temp stability.
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In my 6.5 I havent done this test but in my preliminary ocw test loads under a 140 rdf in peterson brass I hit max pressure at 43.5 which is right around where I did with h4350.
Grain for grain the rl16 was about 30 fps faster at 50 ° than the h4350 numbers gave at 90°.