On my Colt barrel I assume the barrel ends at right before the flash suppressor "begins".  Where does the barrel start, at the end of the chamber?  

Somebody explain it to me in simple terms, small words, and pics if you got them.  Pics make me smarter.

Thanks

To measure barrel length, make sure your bolt is fully closed.  Drop a rod/dowell down your barrel until it hits the bolf face.  Then mark it at the end of the non-removeable portion of the barrel (the end of your flash suppressor if it is permanently attached, the end of the barrel itself if it is not).  That distance, bolt face to end of permanent barrel parts, is the legal barrel length.

Thanks, I had a KKF muzzle brake attached and I had asked KKF to cut the barrel to 14.5 but apparently in the 4 months it took to receive my upper back it was only threaded at the end and not cut.

To legally shorten the barrel under 16" would require the muzzle brake to be permanently attached by blind pinning, welding or silver soldering so that it is fixed and non removeable with a overal lenght of at least 16".

It's a little more involved than just cutting and rethreading the barrel and I can understand a reluctance for a company to do it - especially if you suddenly decided you don't like the now permanantly attached brake.