FBI switching back to 9mm and their reasoning...

[Dean C.]

If I had to carry a full sized duty gun it would be in 9MM for sure, for my purposes CCW I prefer my 1911's as they are very slim and I can shoot quite well with them. It all boils down to shot placement, a .22 in the right spot will stop someone faster than a .45ACP will in the wrong spot.

 

[BE Mike]

Few things are

Please don't set me up like that. It is too much of a temptation to make a wise crack!

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[phylodog]

Please don't set me up like that. It is too much of a temptation to make a wise crack!

​

I'm good with wise cracks, I knew it was a slow pitch.

 

[Hohn]

I've watched lots of tnoutdoors9's ammo test videos, but I don't recall him testing the Underwood 155 grain Gold Dot in 10mm Auto, and I should know because I went through all of them looking for one.
He tested the Underwood .40 S&W with that exact bullet, but unless he has made a video in the last three months (the last time I dropped in on his YouTube channel), he most definitely did not test the Underwood 10mm load with that bullet.
Also, you would be right about a given bullet penetrating less when it goes above a specific velocity, but only if said bullet had a core/jecket separation, which is a failure common to conventional jacketed bullets.
That's why John Nosler invented the Partition bullet, and that's why many modern rifle bullets either overcome that problem with bonding (Hornady Interbond is one example), or by bypassing the issue altogether by not even having a separate lead core at all, as is the case with the Barnes X-Bullet.
Barnes now makes a solid copper expanding bullet for handguns called the XPB, and there are a select few handgun bullets that employ core/jacket bonding.
The Speer Gold Dot is one of the latter type of bullet, as advertised by Speer themselves, and my own unscientific tests prove that, with the jacket tenaciously attached to the jacket, even all the way back over the expanded mushroom.
As long as your bullet stays together, all that extra energy has to go somewhere, and that means laterally into the sides of the wound channel and linearly into greater penetration.
A fully intact bullet that sheds little to none of its own weight and stays in one piece will penetrate more than will the exact same bullet going more slowly, full stop.
That's not opinion; that's simple physics.

read my post carefully; I never said TNoutdoors9 tested the Underwood 155 in either 10mm or .40. What I said was that he tested the factory 155 Gold Dot from Speer. Also that it failed the 12" minimum penetration. Also, that most of the testing he's done shows Underwood loads penetrating less than factory loads of the same bullets.

So, I conclude a hotter load of a .40sw projectile is likely to under penetrate. Maybe not a factor of the slower loading has margin to give (16"+). When starting out at <12", extra speed is likely counterproductive.

 

[oldpink]

read my post carefully; I never said TNoutdoors9 tested the Underwood 155 in either 10mm or .40. What I said was that he tested the factory 155 Gold Dot from Speer. Also that it failed the 12" minimum penetration. Also, that most of the testing he's done shows Underwood loads penetrating less than factory loads of the same bullets.

So, I conclude a hotter load of a .40sw projectile is likely to under penetrate. Maybe not a factor of the slower loading has margin to give (16"+). When starting out at <12", extra speed is likely counterproductive.

Maybe, maybe not.
It honestly makes me want to track down a box of 155 grain Gold Dots (Speer factory) load, then shoot them side-by-side with the same bullet used in my full power reloads.
If only I had some ballistic gel...

 

[hpclayto]

I'd have no problem if my agency went back to 9mm, ballistics now are very good and higher capacity with less felt recoil is a win win.

 

[chipbennett]

I'd have no problem if my agency went back to 9mm, ballistics now are very good and higher capacity with less felt recoil is a win win.

That's what I found to be most interesting in the report.