Try 15 grains difference for 125 to 150fps.I have had no feeding problems at all with my ultramags.Since I don' t use factory loads that is not an issue for me but I can buy 300ultramag loads with 180gr partitions for $55 canadian.Weatherby brand factory loads with 180gr partitions sell for $80 canadian.As for recoil my 300ultramags with mcmillan stocks feel no worse than my 300wby with it' s factory synthetic stock.