Several years ago, I looked up the ballistics tests between the 124gr and 147gr HST, when they came out with the 150gr Micro offering (supposedly optimized for micro/subcompact pistols).I do too. I carry the HST 147 gr standard in all of my Glocks. They have their bullet design down to a science where it expands very well at the lower velocities. Any difference between the rounds is splitting hairs. The terminal performance in ballistic gelatin is equivalent and the 147 has no sonic crack ←FTW.
However, conventional wisdom is, they can use faster burning powder with the lighter rounds without running into chamber pressure issues, so the lighter rounds still work okay even with short barrels whereas (historically) heavier rounds give up too much velocity in tiny barrels.
I have not actually chronographed this to confirm though.
147gr proved extremely consistent, from standard LE duty barrel lengths, to the Micro/subcompact barrel lengths.
No idea what the heck kind of testing Federal did before releasing the 150gr Micro HST, but the 147gr outperformed it (and seemed to perform more consistently than the 124gr, even in shorter barrels), and the 150gr has been discontinued for some time, now.
