I have a question for some of the more seasoned and knowledgeable AR 15 fans. A few months ago I traded a Remington 700 to a Bushmaster XM15E2S. The gentleman I got it from bought it in 1999, and has taken excellent care of it. It's gotten a Rock River trigger and a strange looking compensator. The barrel markings are B MP 1/9 H BAR (I think thats all of it.) Now to my actual question, is this type of configuration rare or does it stand out above others that you've seen? I'm interested to learn more about it. Thanks for your time!