Are you thinking of APP or Triple 7 pellets - and referring to them as "smokeless"? Both of these powders are much "cleaner" than regular black powder, but are still black powder substitutes. Regular smokeless powder, like what is used in rifle and shotgun loads, is obviously dangerous in any MZrifle except the few (two?) that are rated for smokeless. And even then, I'm kinda nervous about the idea.

Your Hawkin is a traditional gun and was designed around using charges up to 100 grains or so. I have one of these rifles, and it likes the medium weight Powerbelt bullets with 100 grains of Pyrodex RS. I have also used the 385 gr. Buffalo Bullet with this same load. If you want "high performance", look into a Knight or T/C inline. And if you want to load smokeless (which I don't personally think is worth the trouble), get a Savage ML II or a White.