As has already been mentioned your throats are on the tight side which increases the likelyhood of leading.

It's a balancing act, between the bullet's diameter & hardness, and the throat's & bore/groove diameter, to avoid leading.

To correct what you said, your throats are somewhere in between .4278" and .4288".

44 bores usually run ~.4165-.4170" which is why your .428" pin doesn't fit. Sounds like you only bought a few pin gages, not the whole set?

If you're going to try cast lead I suggest you go with flat base bullets. Most caster's make bevel base bullets as they're easier to cast (& then release from the mold). The one's that make flat base bullets usually charge more for them because they're more work. The flat bases seal better than beveled bases which helps reduce the gas cutting that leads to leading.

If you "truly hate cleaning the lead out" I suggest you try the HT-coated bullets first & possibly avoid some grief. Otherwise stick to plated or jacketed.

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