I purchased a used ar15 from a friend (stag lower, RRA 11.5" upper in 223 rem) i probly put 200 round of factory ammo through it with no problems. i then started handloading them with my lee pro 1000 and for some reason when i drop the bolt foward it will chamber a round fine but wont cycle the next one it just jams and dents the case. and if it dosent itwont chamber fully and gets suck in the chaber and i have a hell of a time pulling the charge handel to get it out! when it does finnaly come out the neck of the round has this sticky black stuff on it. i tryed my handloads through a friends colt ar and they worked fine i tryed them in an ar10 and they also worked fine i bought 2 new magpul mags still same problem i also bought a speer reloadin manual and all my loads are within specs. im using cci sr primers, reloder 7 powder, speer 52gr bthp, and am triming "once fired" ivi brass to 1.750". i dont know what is going wrong pls HELP!!!


















































