My Handi rifle was the oddball that didn't shoot as well with the 300gr. Hornadys. Quite a few years ago, I found a good deal on a big bulk buy of 405gr. Remington SPs. Dang thing thinks it's a sniper rifle with the heavies. When I pull the trigger on the 405s, I'm wishing they were 300s.
I've used RL7, H4198, H335 and A2015. I used H335 for a while. Accuracy was great and I've killed several deer with that load. One evening I shot a six pointer with it and the flame out of it was like watching an old video of battleships unleashing broadside salvos. Trying to see the deer's reaction was as bad as trying to look through the smoke from a muzzleloader. I didn't have to worry though, he was laying where he stood.
I found a supply of A2015 and 48.0gr. of that powder worked nicely. I loaded five hundred rounds and recently sold the rest of the 405s off. Pretty sure that will be enough to take me all the way out. I've got four boxes of the Hornady 300s for my Mississippi folks when they need a resupply.
I'm sure one of the powders you have will work well for you. If you need another option, 4198 would be a good choice. Enjoy your new rifle.
