If its pure lead, that's probly why its colored.
Personaly, I would try and find some wheel weights and make a mix. Maybe they're hard to find there. You could just add 2 or 3% tin (solder) to the pure lead and have a good mix too. Make it 20/1 or 30/1. I aint tried it myself yet as I have plenty of WW and pure lead, but its been used for MANY, MANY years. I think it makes a more malable alloy vs just antimony.
With gas checks you dont need a real hard alloy. I'm shooting 9mm and 357 at hot loads with air cooled WW alloy and gas checks. As long as the boolit fit is a couple thousands over your bore size, your good to go.