I have used 60 grains of H-870 with good sucsess
in my 270 win.and 130 graih bullets. The case is full. I would like to load sone Sierra 90 grain HP. I can find no data. Anybody have any thoughts ? Thanks

Probably because H870 is too slow for a 90 gr bullet in the 270. Slow powder like that works best with a heavier bullet. I know you'd like to stay with one powder but a faster powder would be better for that bullet.

A case full of it will work fine, but velocity won't be the highest and you'll likely find unburned powder in the bore and cases. (Sometimes enough to cause action fouling problems.) That's actually very popular (usually using the similar surplus WC860 and WC872 powders) for medium velocity cast bullet loads in medium capacity cases like the .270 and .30-06.

Try 53 to 54 grains of IMR-4350 with the 90s.

Oh yeah . . . That H870 is way too slow for any load in a 270. Better send me an e-mail so I can buy that junk off you and use in my 264.