My first handgun was a Ruger Blackhawk .44 mag. which I bought just prior to getting out of the Army in 1980. Only had it a year or three; it was too much for me at the time (might still be too much for me today).
I seem to have bought my firearms in inverse order of usefulness... so my first was a North American Arms mini revolver in .22lr. Still a lot of fun tho
HK USP Compact .40 S&W. It was a month after my 21st birthday. I used my first 2 pay checks from my summer job to buy it. Even though I've added to my collection over the years, it is still my favorite.