I have 4 N frame NRT's but only one for the K frame and I rarely see any K NRT's, I understand that these were the forerunner of "Coke" and then the regular K and N football cutout targets. I remember reading here, as I recall, that they were produce from about 1951-1958 or there about. Was there just very little call for K targets in the early to mid 50's? They don't seem to show up very often.