The most recent Federal 16-gauge shells I've had are purple.
I thumbed thru some old Winchester catalogues and the first picture I found showing a yellow 20-gauge shell was in the 1974 catalogue. However, I seem to recall we were using yellow 20-gauge AAs when I was still stationed in San Diego, and I left there December 1973. I stashed a couple of crisp new boxes of red 20-gauge AAs at home in Seattle on my way to Alaska, but my Father found them and shot them up at Doves in the following years.
Yellow 20-gauge shells are pictured in the 1973 Remington catalogue.
