If the bullet tip had a yellow tip, it would be a 182 grain, lead core, long-range "D" ball. If it didn't have a yellow tip, then it's 148 grain lead core "light ball". To verify the composition of the bullet is lead, see if a magnet will stick to either the bullet or the case.
Steel = stick
lead and brass = no stick
And as oneshooter said, guaranteed to be corrosive.
For a 56+ years old cartridge (1951), how did it perform? Was there any "hang time" after you pulled the trigger?