I shot 124gr 9mm bullets all this year, last year too. But I got a couple of boxes of 147gr bullets and loaded them up recently (same PF) to try them during the lull in shooting here in December. So I went out to the range on Thursday (55 degree weather) with 300 rounds and shot Bill and Blake drills mostly.
Shooting the Bill drill with 124gr bullets I normally hover around 2 secs at 7 yards with .17 splits and a draw that is just above 1 second.
Shooting 147gr bullets today I could not get below 2.25. My draw was the same but my splits were just barely sub .20, if that. I shot about 6 or more strings like this. And it was worse at 3 yards.
It seems to me like I was "waiting" for my gun to cycle with the 147gr bullets.
Two years ago I switched from 124 to 147gr because I liked the snappier feel of the 124s. I wanted to test that impression after shooting with 124s for a couple of years. I confirmed it. It may just be that my gun (M&P Pro) doesn't cycle as fast with the heavier bullets.
Unfortunately, it's something of a trade off. The 147gr bullets are slightly more accurate at greater distances (25-50 yds) in my gun. But not enough to make me switch back.
And that's my amazing, inspiring post for December. Stupid cold weather!