There has been a lot of (sometimes heated) discussion on 124gr vs 147gr 9mm regarding certain barriers, especially car doors. I was wondering if the Underwood loading (or equivalent velocity) of the 125gr Gold Dot would have an edge on penetrating car doors or windshields to the factory loading at 1350fps. The Underwood load seems to penetrate 15-18in in gel, and a few inches less than the factory loading. Apparently Fackler's tests with the factory loading at 1350fps (just about 100fps more than 9mm +P or +P+) did not really do any better.

Underwood claims 1475fps but most of the tests I have seen show it going around 1500fps. So if 124gr 9mm does better on some hard barriers than 147gr 9mm, shouldn't a Gold Dot at 1500fps give a nice edge to someone who operates around vehicles?

https://www.youtube.com/watch?v=iujNWfhUx4A

https://www.youtube.com/watch?v=Z94rLyGvqaQ

https://www.youtube.com/watch?v=w1VNXQKL1uw

https://www.youtube.com/watch?v=ughIFOrIP_w


Regarding recoil, in my Glock 31 the recoil of this load seems only slightly less to me compared to 125gr target ammo at 1350fps. Everyone is different but assuming you trained with .357 sig the extra recoil does not seem to be an issue to me.

Even 100 fps is an edge depending on the thickness of the barrier. For arguments sake, a bullet may be able to penetrate one side of a trunk and not make it through the other side but a little more velocity may make it go through both sides.

You see this in AR 500 armor tests online where a 62 gr failed to go through a vest but the 55 gr at 100 to 200 fps more makes it through with no issues.

It would probably help, especially firing at angles. But to what extent...I don't know.

I have shot a lot of car bodies and windshields (in training) and penetration is inconsistent regardless of the load or caliber. Typically, bullets sail right through, especially at right angles, unless it hits some mechanism or cross bar inside the vehicle body.

I would be comfortable carrying most duty type loads, especially Gold Dot but would avoid extra velocity or boutique loads for duty.

It's a moot point. .357 Sig is too hot for all of Gods children to handle, so it gets shelved in favor of rounds that make it easier for non-hackers to qualify.

With that said, shooting cars is very unpredictable even with rifles. The best option is to keep shooting until the threat stops.

Several years ago a Friend and I did a fairly extensive penetration test on an automobile.  When a bullet penetrates hard objects several things come into play.  Generally smaller diameter bullets penetrate better than larger diameter bullets.  Energy and bullet construction play a large part of penetration.  Bullet weight alone is not a good indicator of penetration and generally bullet energy/velocity and bullet construction play a greater role than bullet weight.

As an example a 115 grain +P+ JHP will out penetrate a 124 grain or 147 grain bullets of the same construction (typical cup & core bullets).   The 115 grain +P+ JHP has more energy than the standard pressure 124 and 147 grain bullets.    Many times a JHP bullet is swaged down to resemble a FMJ when penetrating hard objects.  Vehicle safety glass is very distructive to bullets and a typical cup and core bullet will shed it's jacket going through a automobile front windsheild.  This is one reason bonded bullets have come into favor in LE.

Yeah I think both would get the job done. 357Sig is better than 9mm for sure. But even plenty of 9mm rounds penetrate cars with ease. Of course I'm a fan of 10mm 180grain rounds, even better than 357Sig and I think it's easier to shoot: 

In the tests I've seen on youtube I'd agree I wouldn't trust a car door or windshield to block a bullet, but it seems some do better than others and a lot of experienced LE say it's a crapshoot what will work on a windshield. Best to get several shots off in case one hits a bar or something.

Yeah I like the 10mm too, better guaranteed penetration and in the right platform recoil isn't that bad. I am waiting on a stiffer spring and will be loading 200gr XTP. I am anxious to see how the spring affects recoil as well.