penetration sweet spot

[Moonshot]

When it comes to handgun ammunition selection, following shot placement, I was always told that penetration was the most important factor in bullet performance. I'm only considering tests results from Doc Roberts (and a few select others). We know they used proper testing protocol and their results are valid.

Now, keeping calibers the same and after passing through various barriers, once the bullet reaches the 12" to 18" window and stops, does where it stops matter? At this point (bullet is within the 12" to 18" range), do we start to look at other factors when making a carry decision? Factors such as expanded diameter, retained weight, accuracy in your gun and in your hands, or availability and cost that translates to supply and practice?

If where the bullet stops does matter, what is the sweet spot? Is 17" better than 15"? Is 15" better than 13"? Or, on the other hand, is 13" with very large expansion and full retained weight better than 17" with less expansion or some jacket separation?

I'm not looking to nit pick my ammo choices. After much reading of Doc's posts and the posts of several others, followed by range testing in my guns, I have settled on HSTs in my 9mm and WCs in my airweight. I understand practice is still the key to performance, and I'm not looking at changing things. I simply wanted to understand what the performance data really means. I've frequently wondered if more penetration (within that 6" window) was always better, or if all we want is ammunition that reaches a certain minimum without over penetrating, and anything within that range was equaslly as good.

[Unobtanium]

My opinion is that you want two holes in something living that needs to stop doing. This opinion is based on hunting deer. Deer have 2 lungs, and 1 heart. So do most other mammals on this planet. The rules do not somehow magically change just because that mammal is bipedal. It is also my experience that <1800fps projectiles are equivalent to shoving pieces of rebar through a creature. They don't have magical properties, and they don't damage things they don't touch in places they have not been (exception being a broken bone damaged beyond the point of initial impact, non-elastic structures such as the brain, etc.).

This said, I want something that will through-through the average felon, and still expand as much as possible. Gold Dots have a reputation for being found in perp's clothing having just exited. To me, this is ideal. However, HST has done very well, too. I think at this point, shot placement > minutia. If you for whatever reason shoot HST more accurately, or Gold Dot more accurately, or Hornady Critical Defense more accurately, or whatever...then I'd use that.

I find it interesting how military/police have tried to re-create the wheel that hunters have been rolling for decades. What's the very best barrier-blind rifle bullet in use by the LE/MIL today? Oh. That would be a hunting bullet from the 1980's.

I think that we would do well to look at what hunters have been doing, for the most part.

[PNWTO]

I think at this point, shot placement > minutia.

Pretty much this. I want to reduce the chance of under-penetration so whatever round that will happily punch through with some expanding petals adding to the game is fine with me.

I think that we would do well to look at what hunters have been doing, for the most part.

This is a good point, as there are many similarities in the arguments when it comes to cartridge and bullet selection. Just go to any hunting magazine and read about how the cartridges your father used are worthless now.

Animals haven't hyper-evolved to magically withstand the .270 Winchester and humans haven't gotten their shit together to resist a 124gr 9mm. The key item to the effectiveness of both is a boringly-reliable and unexciting (sorry RIP) bullet design and a good shooter.

[LtDave]

This said, I want something that will through-through the average felon, and still expand as much as possible. Gold Dots have a reputation for being found in perp's clothing having just exited. To me, this is ideal. However, HST has done very well, too. I think at this point, shot placement > minutia. If you for whatever reason shoot HST more accurately, or Gold Dot more accurately, or Hornady Critical Defense more accurately, or whatever...then I'd use that.

My thoughts exactly. I'll use whichever premium load is most accurate in a particular gun. My preference is a heavier bullet, but will use a lighter one if it is more accurate and/or shoots to the sights. I have a couple of 9mm guns that really like 115 gr +P+ Gold Dots.

[Moonshot]

I swear, no matter how long I wait before writing a thread, or how much research I do, if I just waited another freeking day I would often find my answer on my own!

I just read the following, and I think it pretty well answers my question. Thank you to all who responded.

From a 06/2016 post by DocGKR (with the specific answer to my question in bold)...

As noted in the SDPD study and most other OIS incident reviews, bullets in real world shootings tend to have a wider range of penetration than seen in lab studies, for all the obvious reasons previously discussed. In other words, a lot of the time, bullets used in defensive shootings are going to penetrate DEEPER than noted in gel testing (and a lot of time SHALLOWER). In addition, bullets used in the real world tend to act like the 4LD test results.

We have always recommended picking loads that tend to penetrate around 15" or so. The 147 gr HST penetrates about 15.5" in the 4LD test--the test that most closely replicates an unobstructed defensive shooting result. Hmmm, based on that it appears that the HST offers nearly ideal terminal performance for urban and suburban defensive use...

I've said this before - I should read more and post less.

[John Hearne]

Initially, I thought this was another Storm Daniels thread.

FWIW, on chest shots, I really want to rattle the spine. I like rounds that penetrate on the deeper side in hopes they'll have the momentum to make it to the spine and smack it.

[JHC]

Initially, I thought this was another Storm Daniels thread.

FWIW, on chest shots, I really want to rattle the spine. I like rounds that penetrate on the deeper side in hopes they'll have the momentum to make it to the spine and smack it.

I wouldn't mind more options that reliably hit the 18" threshold.

[tanner]

Initially, I thought this was another Storm Daniels thread.

Apparently, we aren't doing "Phrasing!" anymore.

[5pins]

I wouldn't mind more options that reliably hit the 18" threshold.

I agree. As I walk through life and see large people I wounder if the 12 inch min may not be enough.