Never tried Retumbo until recently and haven't done enough work to draw definite conclusions, but initial results have been promising in a new Sendero in 7mm Remington Magnum. I've used several bullets including the 150 and 160 Partitions. Looks like this powder may outshoot H4831, the powder I've used almost exclusively because of good accuracy results for a long time in several magnum cartridges.
Anyone with more experience care to comment on Retumbo?
