Rockymtn: If you mean me, I actually bought it used from a dealer and, now that I think about it, he told me that the local county sheriff brought it in and they went with a larger caliber rifle instead of the AR-15. It had not been shot much as it had not been cleaned when I bought it. I cleaned it. I wonder if the MP would mean Military Police? It's a Colt but doesn't appear to have anything different about it. The markings on the barrel are - C MP 5.56 NATO 1/7 HBAR Thanks.