If you want to know about how well a particular bullet shoots in a 270, load 55 gr of RL19 with the 130 gr missile of choice. Seat (usually) as long as the magazine box will allow. (I know there can be a lot of variation here, so optimize for your rifle.) This is not usually close to a max load, but this is a very specific experiment. It might not be too bad a load for a youngster.
If your bullet doesn’t shoot ‘3’s, try something else. High quality rifles will do it every time.
Hmm. Have found a couple .270s that group 130s more accurately with RL-19 than H4831 or whatever other "standard" powder. One of mine grouped 130s best (including Nosler Partitions) with RL-19--though with around 58 grains rather than 55.
But there are two problems with RL-19. First, it's more temp-sensitive than H4831--or even IMR4350--though not as bad in that regard as RL-22.
The other is finding any--though it's showing up more often on websites than other Alliant powders. If temp-sensitivity isn't a factor, then it's definitely an option.
Have also found a similar load in the .300 Winchester Magnum: 72-73 grains of RL-19 with 165-168 grain bullets. Have never encountered a .300 Winchester that didn't shoot this well, and while velocity is only around 3100 from 24" barrels, with a deep-penetrating bullet that's plenty for most big game on earth.
