I gave 7977 a try today. It was primarily a quick run to get some data. My magneto speed was giving me a hassle, so I will be repeating the test. It might be just the jug I got, bit it is substantially slower than H1000.
My go to load is:
208 ELDM
Norma Brass
CCI Magnum Primer
2.860" COAL at Ogive
78.0gr H1000
MV today was 3080 avg out of a 23.5" Lilja with a can
With 7977 and 208 Hybrid Target today:
77.3 - 2934 avg, SD 12
77.6 - 2949 avg, SD 3 (seemed accurate, but did not fire enough rounds to know)
78.0 - 2960 (Magnetospeed wasn't getting a reading every time and only recorded one shot)
78.3 (very slightly compressed, charge dispensed with no drop tube) - 2971 (same issue with magnetospeed)
No pressure issues with any of these charge weights. I plan on redoing with 77.6 - 78.9 (if it fits)