Underside of the earlier barrels, Made By Douglas, Are Marked with a "D", Later ones were made in Spain, and marked as such. Deer Creek came along later(after CVA went bankrupt, and re organized), bought all of the old stock, and began making 1 in 70" twist barrels, as opposed to the Douglas that are 1 in 66" twist. I have even heard of, and have laid eyes on Spanish barrels made in 1 in 48" twist.
I buy and sell only Mountain Rifles in My shop(CVA and Johnathan Browning), and have handled maybe 200, give or take 1 or 2, in My 10 years of dealing with them. I have observed The "K" on kits, and no "K" on kits. There are many variations. Alot of it has to do with serial number range, and who made the Rifle.
So as with any study, one will find many different variations. I keep a note book on the serial numbers, and changes made in certain ranges. Photographs and a serial number and I can give You a ball park view of who, what, where, when and How. As I would never use the Expert moniker( I believe "Experts" are more full of themselves than reliable information).. I will use the term well informed....