H 870 is old and obsolete but it always works for me in the 7 RM and have about 7 #.
Still have about 8lbs of it and lots of 175s loaded but experimented with R26 anyway. R26 burn rate varies by case size but never use R25 data with out working up, you are usually safe using R22 data but the same warning. It seems to split the difference between 22 and 25 which are really close to begin with but an entirely different powder. R26 could easily equal my 870 loads or slightly exceed them velocity wise and with a cleaner barrel too. In fact if I used the 870 loads and then fired a couple with R26 afterwards most of the carbon was gone and clean up was easier. The verdict is still out on accuracy. Rifles that shoot anything work fine with R26 but the finicky ones don't automatically get more accurate. Slight changes in charge weight don't seem to make much difference so I will tweak seating depth on the next go round.
