I've got a can but haven't tried it yet. Everywhere I crossreference it it seems to be a virtual twin to re25. Not quite as slow as h1000...but faster than 7828. I tend to think re25 can be just a little spikey so I'm hoping that 7977 is a just a little better with the temp stable stuff and copper reduceer.
No but have shot a lot of RL 26 in 280ai. I would think looking at load data for other calibers that 7977 and Rl26 are quite similar. Starting at guessing around 55gr with the 160AB and look for max speed at about 2,900-2,950 +/- would be reasonable method. I did have better accuracy with the 215 primers across the board when testing the Rl26.
With that said I have ended up back with the 140AB's using 60 grains IMR4831 with 210 primer. It is just a magical sweet spot in the accuracy department for the 27" brux barrel on this gun and easily hits 3,275fps. There is not enough BC difference in the 2 bullets to matter to 600yds +.
