Barrel installation: Depending on your receiver, if there is paint build up in the receiver where the barrel extension is inserted, be sure to scrape that out. If the barrel is tight, use an anti-seize compound to assist in installation. It is best if you can get the barrel started, then turn it over and tap the back of the receiver with a rubber mallet. Be sure to line the extractor slot up as you are installing the barrel. Your barrel is ready to shoot, just run two magazines through it before you really start looking at group size. Do this each time you change brands of ammunition as well. Keep the chamber clean, but don't clean the bore too much you will decrease accuracy. Depending on the ammo, clean the bore around every 500 rounds.