How did the sling get in the way JTR, I am curious what the specific problem was? I am a lefty and use the standard release like coldblue mentioned, mag release with right hand thumb. I use the charging handle to release the bolt (major motor skill) not the bolt catch (minor motor skill). I reach under the rifle with my right hand and grab the charging handle, I have one of those "tactical" latches that works pretty well for me. This process is a bit slower when compared to using the bolt catch, but it's a more sure thing under stress. I have seen fellow students stuggle with fine motor skills in high stess drills. I try to keep my left hand grip position in the same place and not move it around at all. As far as unintentional mag drops, a tug on the mag must be incorporated in to the realoading process. I have learned this from some very embarassing unintentional drops, all in a class environment thankfully.