If retail sources are not available you just might consider having someone handload Nice shot.
I checked the Nice shot web site and it had #5 shot available. Ecotungsten (Nice shot) uses lead handload recipes and someone might just be able to handload some loads suitable for your new LC.
I've got a 1946 field grade featherweight that I have degreased (stock) and glassed reinforced. I am loading Nice shot with blackpowder for duck hunting next week.
I had great success at the trap range with these loads (smashing clays with authority).