Originally Posted by mtgianni

Some of the manuals are using swedged bullets rather than cast. Frequently the Lyman Handbooks show higher charges for cast than jacketed as there is less friction moving sown the bbl. Less friction also results in less pressure so the amount of powder is increased, increasing speed and resistance from friction.
Not all manuals due this, some because of their ballasticians, some because of the marketing of cast projectiles they are not selling.

I am not sure about flame temps and leading. I have experimented by putting a dab of grease on bullet bases before loading and firing. The grease is still present on the bullet when it's recovered. If it won't melt grease I have a hard time believing it is melting lead.