I originally ordered a 22lr upper from CMMG. I cancelled the order when I discovered that they did not build the uppers until they were purchased and had no idea how long it would take. So, I ordered one from Midway – they had them in stock at a much better price. I also ordered one Black Dog magazine. The CMMG upper worked real well. Then the fun began. I did not like the hand guard and obtained a Hogue free float tube. I popped the hand guard off and proceeded to take the barrel off – no way would the nut budge. Later I obtained proper tools, locked it in a bench vise and could not budge the barrel using a DPMS tool and a ½ inch drive ratchet with a two foot pipe for leverage. My Son and several other people who have experience in this area also tried and failed to remove the barrel. I bought this thing because it consists of modular units that can be modified at will, so if the barrel cannot be removed it becomes useless to me.