For muzzleloaders pure lead is the way to go when ramming the ball/bullet down the barrel. I used some plumber's lead, which is pretty soft, years ago in an attempt to conserve the pure and after the first shot I could not push the conical bullet past the fouling, whereas the pure lead allowed me to easily load 20 in a row and retain good accuracy. To complete loading in that instance I put the ramrod against a block wall and tapped the ball down using the weight of the rifle. Not recommended as a normal loading practice. I've read where some have used an alloy mix to harden their balls, but my guess is that they are casting undersized and use a thicker patch to accommodate the hardness of the projectile. I'll do my best to stay with pure lead if at all possible.
If the 44 is for a revolver then a bit harder ball shouldn't be an issue because of the force of the loading lever. Still, even then, too hard would make even that difficult when shaving the ring off as it enters the chamber.
Wax from a candle fluxed thousands of slugs for me. If I am melting large quantities for ingots and it is dirty lead than pine shavings from the table saw works very well, too. If fluxing indoors be aware much smoke is made in this process.
Enjoy the learning curve. There is a cadence to this task to cast good balls/bullets with out wrinkles and voids. Once you gain the feel and timing you'll receive much satisfaction from the product you'll turn out.