I have recently kind of become interested in shooting 22 LR at long distance. I wanted to see if I could get some answers in here. Many times I will take my various brands of 22 LR bullets out and look for the tightest group(s) to try and narrow down which one I need. One thing I have noticed is that a certain brand will shoot a real tight group and I will continue shooting through the various brands. At the end of shooting I will have about 3 brands that shot better. I can then shoot groups with these and many times the groups are worse than the ones I have already eliminated. Very frustrating. Does this have to do with the fouling in the barrel? Does this have to do with the barrel warming up (I would not think so in a 22)? I've even heard that some 22 ammo leave residue and wax in the barrel that will effect further rounds going down the barrel. Any suggestions?