You have a "CAI"
M1 rifle, not "CAT". They were produced by CAI, a US ddistributor, about 8-10 years ago, using a new cast receiver & used USGI parts. They originally sold in the $400-500 range, but prices dropped when the shooting community saw how bad they were. I haven't seen any with
Danish barrels, but I guess it's possible, or, most likely, a previous owner changed the barrel. The problem is, the receivers are usually far from milspec dimensions & the metallurgy is suspect. Plus, many parts are badly worn. Most do not function reliably. The 2 I have worked on could only be taken apart with a set of pin punches & a mallet. My opinion is that they are unsafe to fire under any conditions other than "life or death".