CLEAN
Water ... room temp, NEVER warmer to hot!

SOLVENT
If I need to use a solvent, Butch's 'Bore Shine' for black powdah is phenomenal, best I have ever used!

STORAGE
Short-term: Ballistol.

Long-term: Birchwood Casey's 'Barricade' product.

Ultra-Long-term: RIG grease.

All of my MZL'drs will shoot into ONE ragged hole ALL day long ... it's just those darn 2nd & 3rd+ shots that tend to open up my groups!