Not sure when exactly it changed, and couldn't find an active thread. I'm late to the party on this change and recently learned the case I just bought of HST 147 is a different bullet than my beloved carry round. Has two cannelures vs one. What I've learned reading here and watching around for an hour is that, SUPPOSEDLY, correct-me-if-I'm-wrong-and-I-know-damned-sure-this-forum-will:

The second cannelure was added to help prevent jacket separation (didn't know that was an issue)
The newer rounds are averaging slower FPS vs old
The newer rounds don't expand as well vs old

So is the consensus that the new HST 147 is g2g, just not quite as g2g as the old one? Still happy with the HST 147? Or what are folks thinking/doing like are people/departments moving into or out of the HST 147 based on the change?

Critical Duty 135 gr +P.  

Fed 147 gr HST regular and +P, 124 gr HST regular and +P, and Speer GD 124 gr +Ps don't perform as well in the six FBI protocols that I've seen during demos.  They would fail to go the required depth in windshield and car body test, hence the additional cannelure.  
Still adequate, but not always 100%.

@doktarZues

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Is this the ammo on sale from Bereli?

I'm sure it's most if not all HST 147 you can buy commercially as of now is the new style. but the case I speak of does happen to have come from Bereli. (They're blowing them out at $500/shipped.)

I figure it will take me a few years to practice and cycle through what I have and this case. By then there will be a new celebrity round Honestly though I will probably always be in a standard pressure 147. They seem to shoot softer lending to more accurate follow up shots (at speed). I'm sure these new ones will do their job just fine if called upon.. just curious what the hell they did to it!

Also, assuming it's safe to hijack my own thread, were there any bullet changes to the HST 124? Same bullet same velocity as the older style 124? Seems like it as I can't find any posts anywhere about it changing, but nor can I find any confirming that.

Id consider the new design an upgrade.  HST isn't bonded so you will get better expansion but it's not going to do as well with barriers.   It's always a trade-off.

That’s why Ive always liked HST as a regular ccw guy.

I can see why LE needs better barrier penetration, but the likelihood of me needing that is so minuscule that I think expansion is a higher priority.

Hornady Critical Duty 135gr +P is the approved load for the Bureau.  It performs great thru barriers and then opens and penetrates consistently in flesh/10% ballistic gelation.  Lots of LE agencies are following suit with FBI ammo selection for performance and logistical issues.  As a self defense load, you'll be fine with 147 gr HST.

Precisely why I practice with the new stuff and keep the old stuff for carry. The new stuff isn't an upgrade for me.

My department noticed the lackluster expansion after the change.

We reevaluated and ran a full selection test to FBI protocol

We settled on the 124gr +P and switched to it over two years ago.

It has performed well in numerous OIS.

Basically the HST and Gold Dot are great performers but different calibers and weights can have small effects on performance

Probably about 10 years ago, there was a big push for increased penetration through barriers .vs expansion and terminal performance. I have asked repeatedly if anyone knew of any data or a specific incident that led to this change and I have yet to hear anything. Maybe there are incidents where 9mm loads have been stopped by car bodies or glass but I have not heard or read about anything specific. Maybe the new generation finally read about the 86 Miami shootout...

As a result, HST lowered their velocity by a little, maybe 20-30fps and then added the second cannelure in limit expansion, increase penetration.

Mediocre loads like the Critical Duty are now all the rage, expanding less than most other loads.

I strongly suspect this move is driven primarily by marketing rather than any actual feedback from the street. Maybe it has to do with the country-wide shift away from the 40SW, which always did well through barriers and now all the new 9mm adopters are feeling anxious about penetration.

If you prioritize expansion (.65") and can live with less penetration, (closer to 12") then the HST is probably the best for you. If you prioritize penetration, (closer to 18") at the expense of expansion, (.55") then Critical Duty.