One thing I noticed, Jacko - is that you may not have sized and lubed the bullets immediately after casting them. Doing so will not anneal the bullets. While quenching the bullets will harden them in relationship to the temperature they were when quenched, cold working the bullet, ie: sizing, will soften or anneal the bullets if not done immediately after casting. If they sat for any length of time over 12 hours, it is likely the contacting surfaces in the size die were softened back to original hardness of the alloy.

I like a rifle's cast bullets to be .002" larger than the groove diameter.