Lead core trolling line sinks extremely well, but it's difficult and potentially dangerous to cast. BTDT. With the wealth of lines available these days I'd avoid lead core. LC13 is plastic coated and handles better.

I have RIO sink tips in type 3, 6, 7, and 8 plus T-8, T-11, and T-14 in a 15' length. That with a lead dumbell eyed fly and I can scrape the stones on the bottom of any river I want to fish.

Sg