Welcome to the forum DJC
I've never had a handi in 223, but I've loaded for 7 bolt guns, and my experiance (which may or may not be relevant) is that a load that shoots a 50 grain bullet 2850-3100fps will work. I've had best accuracy using 50 grain and under bullets, the exception being the Winchester 64gn bullet. Remington's 50 grain PLHP is a great bullet for accuracy, and they're dirt cheap. Also hold together better than the ones with the polycarbonate tips.
Best powders, AA-2230, H-322, BlC-2; IMR-4895.
I like to keep my brass separated by manufacturer.