YEs, Many rifles, especially those with thin barrels, will heat up after only two or three shots and start stringing them out. Remember that as the barrel heats the steel begins to expand and get softer and this will absolutely change how the gun shoots. Also, the hotter the barrel is when you fire a shot the more that bullet and powder is eroding the barrel.

Shoot no more than three shots and let the barrel cool down for about five minutes or more. I like to shoot one shot, let cool for two or three minutess and shoot another shot, etc... etc... There should be no need to clean the barrel after only 6 shots. It is the heat that is most likely causing your problem.