greetings and welcome to the Forum, simply put the "alpha cats" are the early Bearcats that used the letters of the 'alphabet' in their numbering, starting with the letter 'A-001' and thru to "Z-999" (3 -digits) the letter O was not used as it appeared to be a "zero'.......these early ones are usually considered more of a value, but "condition" is still first and foremost in ANY grading......... 8)
for a more 'detailed' and complete explaination, one should read any one of the MANY books written over the years on the Ruger single action revolvers........ :wink:
Watch out. That is how I got started collecting them. My first Bearcat was a "alpha cat" K-817. Got it, and the box, and the original sales slip, and the users manual for $325.00. Picked up E-123 a while later. Always on the lookout for the next 'right' one.