Several weeks ago I traded for and started shooting a 66" 41# bow. This is considerably lighter than I have shot in the past. My shooting has improved and I believe my form has also improved. I have, however, encountered a slight problem that I can't seem to get a handle on. When I first start a shooting session, I seem to be inconsistent in my draw length. I'm reaching full draw and a solid anchor (corner of my mouth) but sometimes I seem to draw the bow further than other times. I think it has to do with whether I fully flex or stretch my back muscles (if that makes any sense). It also may be that I am inconsistent with my left arm and shoulder extension (if that makes sense). Anyway, I can definitely tell when it is happening and my impacts are erratic up and down. After 10-20 shots I seem to settle in and become consistent and all is well. Does anyone understand what I am trying to convey and have any suggestions?