I have a used (broke in) Kimber Pro Shadow LE II. I have had 2 occassions where the last round in the magazine chambered in front of the extractor which prevented the slide returning to battery. The magazines I use are Wilson 47D and have less than 500 rounds run through them. The first occurance happened when my daughter was firing th eKimber, and the second time happened to me on different trip to the range. I do not know what the round count is for the Kimber. I have plans to replace the springs in the pistol. Is this out of sequence chambering the result of a weak recoil spring?