When I load up the 5 round flush mount mag it seems like you can almost fit a 6th round in it, just barely doesn't fit. Do you think the spring could be clipped a little in order to squeeze that extra round in? I know this can be done with certain rifle mags.

I wouldn't do it. It's designed for 5 rounds and by removing some of the spring you could diminish the reliability of your magazine. I carry a second mag in an old nylon knife case that I modified with a metal belt clip. With a carry firearm it's best to be safe than sorry.

I have never heard of anything good happening from cutting the spring.... Normally Nose dive FTF's on the last round are the result......