Is there any chance that the primers are different between Non-LE and LE?
I have been using Non-LE and since my R9 got it's new slide (original cracked) and a stiffer trigger spring (I believe) I have had no light strike failure to fires. I bought a case of 124 gr LE a few months ago and since have hade numerous light strike failure to fires. All these rounds would eventually fire after a second or third or fourth trigger pull.
Craig T.