Question for DocGKR: 9mm, .45 & Windshields

#1
I am a courier who is frequently tasked with transporting very expensive medical equipment on a time-critical basis. While the company I work for does not issue firearms, we are allowed to carry our personally owned firearms on the job, and it is commonplace to do so. For over a decade I have been carrying my Glock 19 while making deliveries, but my research has led me to question whether I would be better served by a larger caliber because I spend most of my time behind a windshield (frequently at night and in high-crime areas). I’ve seen you recommend .40 S&W 180gr for police work around vehicles because it has less deflection and less chance of under-penetration after shooting through an automobile windshield compared to 9mm. However, your research has also brought to my attention the array of modern 9mm loads that can penetrate adequately after going through a windshield.

I practice at least once a week, usually firing at least 200 rounds. Switching to .40 S&W or .45 Auto would cost me more to practice with, but not prohibitively so, and I’m wondering if I should switch or continue with 9mm.

I currently already own a Glock 21 Gen 4. At the range I can’t discern a difference in ability to shoot accurately and quickly between the 21 and 19. However, shooting quickly and accurately at the range is a lot easier than in a self defense situation with a moving target, especially if I must shoot one handed.

Firstly, I’d like to thank you for publicly posting much of your research findings for us all to see. It has very likely saved lives and has guided my ammunition choices for over a decade.

Secondly, the crux of my question is: Do the larger, heavier calibers give a significantly better likelihood of a successful outcome in a shooting incident involving auto glass, so much so that I should switch? Do the advantages of lower recoil, (potentially) faster, more accurate follow up shots, and higher capacity of the 9mm outweigh whatever advantage the .45 has in penetrating after auto glass? I’m also asking on behalf of several of my co-workers wondering the same thing, and we appreciate any insight you may have.

(I currently carry Federal HST 147 grain, but I try to get Winchester RA9B when it’s available because of it’s track record through windshields.)

Thank you.
 

Mike_IA

Member
Network Support II
#2
In our agency testing RA9B failed 3 of the FBI barriers and only 1 of 3 rounds fired made it into the gel after going through glass, testing was done in 2015 to FBI protocol. Similarly RA9BA failed 2 of the barriers- 1 round didn’t make it through the glass and all rounds fired at steel exited an 18” gel block.

Federal HST 147grn over penetrates on the steel barrier and under penetrates on glass.

124 and 147 gold dot fail 2 barriers as well. 147 over penetrates steel and plywood. 124 under penetrates bare gel and over penetrates steel.
 
#3
Understand that working from inside out of a vehicle, bullets tend to deflect quite aggressively past several feet. As an example at about 20-25 feet past a windshield 9, .40, .45 have sufficient deviation to entirely miss 18"x36" targets. This is due to the glass disrupting the round early on it's trajectory, rather than the testing parameters for ballistics at the end of the bullet's path. It is definitely better to shoot over, under, around rather than through any barrier, if possible.

In having to shoot through windows in that manner, it's reasonable to treat the first one or two rounds as sacrificial to establish a port to shoot remaining rounds through.

Working from outside in, there's only so far in a vehicle that pookie can be and you still have a viable shooting lane. In most cases it's mere feet from glass to target, with much less distance for the deviation of the round to manifest.
 
#4
In our agency testing RA9B failed 3 of the FBI barriers and only 1 of 3 rounds fired made it into the gel after going through glass, testing was done in 2015 to FBI protocol. Similarly RA9BA failed 2 of the barriers- 1 round didn’t make it through the glass and all rounds fired at steel exited an 18” gel block.

Federal HST 147grn over penetrates on the steel barrier and under penetrates on glass.

124 and 147 gold dot fail 2 barriers as well. 147 over penetrates steel and plywood. 124 under penetrates bare gel and over penetrates steel.
Thanks for the reply, Mike. Those are interesting results. Were there any loads that passed all tests? If you tested other calibers, did they fare better? Perhaps RA9B isn't all I've thought it is.


Understand that working from inside out of a vehicle, bullets tend to deflect quite aggressively past several feet. As an example at about 20-25 feet past a windshield 9, .40, .45 have sufficient deviation to entirely miss 18"x36" targets. This is due to the glass disrupting the round early on it's trajectory, rather than the testing parameters for ballistics at the end of the bullet's path. It is definitely better to shoot over, under, around rather than through any barrier, if possible.

In having to shoot through windows in that manner, it's reasonable to treat the first one or two rounds as sacrificial to establish a port to shoot remaining rounds through.

Working from outside in, there's only so far in a vehicle that pookie can be and you still have a viable shooting lane. In most cases it's mere feet from glass to target, with much less distance for the deviation of the round to manifest.
In having to sacrifice one or two rounds to establish a port to shoot through, would you say that 9mm creates an advantage in that you have more rounds left after creating the port?

It sounds like shooting from inside a vehicle out, your target would have to basically be on the hood of the vehicle for a probable chance to hit, is that correct? Thank you for your reply.
 

Mike_IA

Member
Network Support II
#5
We tested Winchester, Remington (Golden Sabre), Speer, Federal, and 135gr +P Hornady Critical Duty. The Hornady performed the most consistent and was up selected. FBI ended up with the same results. And we re-tested that Hornady round in pistols with shorter barrels against another 124grn round this October and 135+P came out on top again.

When shooting through glass you are actually firing 2 rounds the one that leaves your barrel and the one that leaves the glass- both have completely different weights, velocity, gyroscopic spin, trajectory, etc. so your practical solution is get the gun through the glass or create a port as was previously mentioned.

Another bit for thought in as little as 1” from the hole in glass (even though it is spider webbed) glass will go back to having practically the same effect on the bullet as clean glass. So you have to get the bullet cleanly through the hole you punched.
 
#6
We tested Winchester, Remington (Golden Sabre), Speer, Federal, and 135gr +P Hornady Critical Duty. The Hornady performed the most consistent and was up selected. FBI ended up with the same results. And we re-tested that Hornady round in pistols with shorter barrels against another 124grn round this October and 135+P came out on top again.

When shooting through glass you are actually firing 2 rounds the one that leaves your barrel and the one that leaves the glass- both have completely different weights, velocity, gyroscopic spin, trajectory, etc. so your practical solution is get the gun through the glass or create a port as was previously mentioned.

Another bit for thought in as little as 1” from the hole in glass (even though it is spider webbed) glass will go back to having practically the same effect on the bullet as clean glass. So you have to get the bullet cleanly through the hole you punched.
Perhaps I should forgo moving to a .45 Auto Glock 21 and just buy some Critical Duty 135gr +P if an optimized .45 load does not offer enough of an advantage to be worth it?

Sounds like planning to shoot through the hole you create with from the first/second shot through auto glass isn't a very realistic solution, as I doubt many could accurate place a round through such a small hole with so many factors in play.

Overall it sounds like shooting through auto glass doesn't usually go well under any circumstances, and like you both said, it's better to move the gun to shoot without that barrier.
 

MrMurphy

Regular Member
#7
Currently carrying a 21, agencywide going to 17s... despite 20 years of carrying .45s, i am quite happy to have more rounds.

In your case i'd say keep what you got, carry more reloads.
 
#8
Sounds like planning to shoot through the hole you create with from the first/second shot through auto glass isn't a very realistic solution, as I doubt many could accurate place a round through such a small hole with so many factors in play.
Working ports is applicable if you're in the vehicle shooting outward, as it sounded like that's a viable concern from your initial post.

Working a threat inside a vehicle, unless you're shooting a dude down the long axis of a bus, they're going to relatively close to the window, windshield, barrier.
 
#9
Working ports is applicable if you're in the vehicle shooting outward, as it sounded like that's a viable concern from your initial post.
Good point. Does placing several shots through the windshield around roughly the same area create a large enough hole to clearly aim through, being laminated glass that tends to stick together? I practice frequently, but I doubt under stress I could reliably put multiple rounds through a bullet-sized port hole if it's only about .35" in diameter.

Regardless, it seems like depending on a pistol bullet to still penetrate enough after going through a windshield is a shaky prospect, and one should do whatever they can not to fire from behind a windshield.

Currently carrying a 21, agencywide going to 17s... despite 20 years of carrying .45s, i am quite happy to have more rounds.

In your case i'd say keep what you got, carry more reloads.
Yeah, I'm beginning to think I really am better off with more rounds even if the .45 would perform slightly better from behind auto glass... More of the testing I've been seeing seems to point to all of the standard service calibers having sporadic results after passing through a windshield.

If this is an incorrect conclusion, someone please say so.
 
#10
124 and 147 gold dot fail 2 barriers as well. 147 over penetrates steel and plywood. 124 under penetrates bare gel and over penetrates steel.
I'm curious, was the 147 Gold Dot the G2 or the original version? How did the 147 do against auto glass, and 4 layers of denim? Also, was the 124 the +p or standard pressure?

I have some boxes of original 147gr Gold Dot for when HST isn't available, so I'm wondering how well it performs.
 
#11
Good point. Does placing several shots through the windshield around roughly the same area create a large enough hole to clearly aim through, being laminated glass that tends to stick together? I practice frequently, but I doubt under stress I could reliably put multiple rounds through a bullet-sized port hole if it's only about .35" in diameter.
It's effective but Mike explained above a bit:

Another bit for thought in as little as 1” from the hole in glass (even though it is spider webbed) glass will go back to having practically the same effect on the bullet as clean glass. So you have to get the bullet cleanly through the hole you punched.
Regardless, it seems like depending on a pistol bullet to still penetrate enough after going through a windshield is a shaky prospect, and one should do whatever they can not to fire from behind a windshield.

If you haven't already done so, you might look up Will Petty's VCQB videos. He's got a good one on Vimeo.[/QUOTE]
 

Mike_IA

Member
Network Support II
#13
I was speaking about Gold Dot. G2 is a whole separate issue, and was dropped by the FBI after a re-design attempt.

Porting a window works from inside out. Barrier Tests were designed to look to see if the bullet could work outside to inside.

Shooting through glass works and sometimes is the best option, but you need to know the impacts and limitations that go with it.