Started with shotgun shells because I was shooting (or trying to) competitively (Those $6.95 16 gauge shells were EXPENSIVE!) Bought Mec 600 after I won an 8 lb keg of Unique. Then expanded to 12 gauge because I could get the hulls for free just by picking them up. Winchester AA's and Remington Blue Magics were the bomb back then.
Turned 21 and bought a S&W 19-6 and to shoot more (that $5.95 box of 357's was EXPENSIVE!) I borrowed a friends Rockchucker press. Bought the dies and went after it.
Expanded to my 25-06's then my Dad's 30-06, then the 30-40 Krag, then ...
I now reload for every firearm I own save the rimfires.
