I went to do some target practice the other day. Out of 50 rounds , seven didn't chamber completely. All 50 rounds were reloads , I resize the brass then trim to length .When i was done shooting , i pulled a bore brush through a few times , a dry patch, then a patch with some oil on it, breech to muzzle.The next day i decided to give my M1 carbine a thorough cleaning. I ran a patch with some solvent through the barrel muzzle to breech, I pulled out the patch and found these little black rings, after i cleaned them they appear to be brass. Has this happened to anyone else?