I was 12, when I was part of the Junior NRA Club, on Otis AFB. They were organization-owned Remington .22LR Target Rifles.
I was 18, and in my 6th week of Basic Training, at Lackland AFB, and issued, a Colt M-16 rifle. One day instruction, one day qualifications. (Thanks, NRA!!)
I was 20, stationed at U-Tapao RTNAF, and issued a Smith and Wesson M-15 Combat Masterpiece, and another M-16, with which to guard "the back 40" of the airbase.
I was 31, when I actually laid out cash, and purchased a British Enfield SMLE MkI, .303 British caliber.