I have a new barrel for my Avenge-X in .25 they did not come with the 3 O-rings for the breach end of the barrel. I have my O-ring set that came with my gun. So I need to know how to put the O-rings on properly and which ones to choose to go with the three little slots for O-Rings towards the breach end of the barrel. Some O-Rings are different color (the smaller ones), the larger ones are black and obviously don't belong where I need the 3 to install.