Best powder I've used for reduced loads in high powered rifle cartridges is trail boss. Very safe bulky powder. Cant overcharge the case. Wont get erratic ignition (like you can with smaller quantities of faster burning powder). Try a can, you'll love it.
Hodgdon has a formula for using TB that is idiot proof in rifle cases on their website. Ed Harris has developed loads using Red Dot in reduced rifle loads. Google Ed Harris and Red Dot and it should come right up. SR4759 is a bulky rifle powder made specifically for reduced rifle loads. Lyman has lots of data using Unique and other pistol powders with cast bullets.
I don't own a 30-30 so I can't give you any info based on personal expirience.
Well if you use the starting loads with most powders then you already have a reduced load for the 30-30! I have loaded alot of 30-30 and these starting loads reduce recoil alot with jacketed bullets! Want further reduction then use cast bullets! If your really have a problem with recoil maybe getting a better butt pad is the answer! I own both Winchester and a Marlin, the Winchester butt design is slimmer then the Marlins and you definately feel more recoil with the Winchster! Problem solved with a Limbsaver!:supergrin: