Howdy from washington

I've been shooting BP inlines for several years now but never satisfied with my accuracy so being the reloader I am I started casting and making the best most accurate conicals possible (not very successful. Present molds Lee 250, 320 reals, TC maxi ball 370, Lyman Great Plains 395, unused lee .501 450 and .515 440gr.

Welcome to the brotherhood

Follow IdahoLewis method of casting and you'll be making perfect conicals in no time.

After seeing idaholewis on youtube I have no doubt I've come to the right place.

Welcome. The bullets mentioned have been around for a while and some have good success with them. However, that being said, there are several better bullets out there. We are all trying to find the holy grail bullet if you will.
I've tried everything from some of the ones you've tried, and other full bore conicals and paper patched bullets. I've still searching and many of us in here send bullets to each other to try.
Thing is, not every muzzleloader will like the same bullet. Bore size is a critical factor in determining the correct bullet diameter. That is why most slug their barrels and get custom molds made.
Also when we do cast we sort out bullets looking for any obvious imperfections and also weighing every one and keep them within 1 to 1.5 grains of each other. Our powder charges are weighed not just poured and we are as consistent as possible in our loading technique.
Now we all can't shoot 1200 yards and hit steel like Lewis does (I never tried and likely never will even if I could find a place to shoot that far). But he has the equipment to do it. His sights cost as much or more than his rifles but that's his thing and he's good at it.. I know personally with my fading eyes it would be pure luck.

Even some of us casting nuts like to have our bullets weigh within a .5 grain.