no not much blowby as i do not resize the cases and i also use full power loads.
i use SPG lube but you can make lube that will work very well;
1- 1/2 bee wax 1/2 clear vasoline ... this is mixed on a very low heat till all melt together and stir for around 3 minutes to mix well ... then allow to cool.
2- 1/2 bee wax again and 1/2 lamb or sheep tallow ... mix the same as above.
3- 1/3 bee wax 1/3 unsalted crisco 1/3 olive oil ... mix the same.
the above mixtures can be made softer or harder as needed by adding bee wax for stiffness and oil/tallow for softer as the case demands.
the original Sharps recipe called for 1/2 bee wax and 1/2 whale tallow and mix richer or leaner on the tallow for the stiffness desired ... now go forth and find whale blubber to cook down for the tallow