Hey everyone, it has been a while since I posted last but recently ran into a problem with my AR.

I was shooting and as I pulled the trigger three rounds fired at once (like a three round burst) except that my rifle does not have that option. I then took the rifle home and gave it an immaculate cleaning. A couple weeks later I took it back on the range to see if it would function normal and the problem happened twice in about 400 rounds.

Can somone suggest possible problems and who can look at it for a good price? Where do people buy parts for their rifles at good prices as well?

I am in the Denver/Aurora area.

Thanks for all the help in advance.