Over penetration vs. barrier penetration in reguards to defensive ammo selection

I have been looking into defensive ammo for a few years now and, something I see discussed over and, over is over penetration. However, I rarely see anything about barrier penetration. I’m pretty much still on the fence on the subject of which is more pressing.

With the subject of over penetration my pondering is this. What if there is an innocent person behind the threat and, if so, should the shot be taken in the first place or, should you wait for a better opportunity?

With the subject of barrier penetration my pondering is this. What if you have an opportunity to stop a threat but, there’s some sort of barrier in between (for example a glass store front in a shopping mall). Will your chosen ammo not only penetrate the obstacle but, retain the ability to be effective against the threat?

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If at all possible when there is an innocent behind the target i would rather not take the shot but if it is going to increase the risk not too then i would try and play the angels if dropping to a knee and shooting upward would decrease the chance of hitting an unintended target, ect. I will usually carry two types of ammo that i personally like as well frangible hollowpoints for less chance of over penatration or accidental collateral damage sfter hitting a wall, but i also carry critical defense for better penetration if something like glass or light cover is an issue. I have thought about changing from critical defense to critical duty for better penetration but have not yet.


Firing a weapon with friendly people around has got to be the hardest decision to make. It really comes down to your skill level. Not just how accurate you are but your decision making skills.

Shooting thru an obstacle it will be impossible to know what the round will do after it breaks the barrier. Shooting thru glass your basically using the first round to remove the barrier. Shooting thru a more solid barrier you have the chance of the round at least creating shrapnel.

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If its glass or wood, i know id rather remove the threat a alternate way, or reposition for a clean shot… different barriers have different effects on rounds in flight no matter the distance. So, id stress moving over shooting through, especially if there are innocents under the window…

Hypothetically speaking, what if avoiding the obstacle was not an option?

We must also take into account Accomplice Liability laws. If an innocent is harmed, while there is a felony being committed, the instigator and committer of the crime is liable for the injuries. We “good” guys/gals might still end up in civil court, but, we shouldn’t be charged with a crime.

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Thad… if it was unavoidable… id break the glass with my screwdriver tip, then take the shot as accuratly as possible… but even at close distance, thats a crap shoot whether the “hostage” if applicable at that point would get hit…

If you’re basing you’re tactics on my original hypothetically scenarios, I never said anything about a possible hostage. In the barrier scenerio that I mentioned, I used the glass store fronts such as used in shopping malls which are rather thick, resilient and, not likely to shatter if hit with a screwdriver.

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Roger… sorry the details escaped me… i vuilt a senario around highest probability…

No problem, I am enjoying your participation in the discussion. I may not have been clear enough in my opener. What I am asking is, what are people basing their defensive ammo decisions on in the context of over penetration prevention or, the possibility of needed barrier penetration.

Well i know if im carrying my 9mm i have 64 round to play with so if i take a barrier out with 2 im still good… my 1911 i carry 33 rnds, so 1 round and the but of my weapon… both if needed, if i can get away without discharging, i will happily…

To limit over penetration, I would focus on a lighter grain/normal load. If I want barrier penetration, I would probably choose a caliber more suited, such as a 357 SIG over .45. For EDC, I think the chances of over penetration are much greater than barrier penetration, so I carry accordingly. Avoid collateral damage, and react according to the situation.

**Remember, we can only use lethal force if there is an imminent, unavoidable danger of death or grave bodily harm. If there is a barrier between myself and the attacker, I’m outta there! I’m not going to try to get through that barrier.


I’m a member of my chruch security team. We’ve talked about barriers in and around the church.

In my EDC role i agree im putting time and distance between me and the threat.

While on the security team its a completely different roll.


@Dawn, I fully agree with everything you just said. I’m just curious if people think about those things and, if so what are those thoughts.

@Thad It’s a great thing to think about. We will never know all the variables of an encounter better to think about and kinda have a plan or idea then too freeze when everything matters more


I was lucky enough to do a Proving Ground for the USCCA (you may have seen the training broadcast about the convenience store robbery - that was me :blush: ). My instinct was to get the hell out of there!

As I was going for the door, I heard Kevin’s voice saying never turn your back on a loaded gun - which is exactly what I had done. (Kevin had reminded me before the training.) I was able to turn around before he could shoot me. I did fire in defense - and after the fact could not remember how many times I had shot. Adrenaline is a funny thing - even when I knew there was going to be trouble.


@Dawn. Adrenaline is a remarkable thing. If you train enough it can be used to save your life, if you avoid training where your adrenaline gets going it very well could cause to freeze up and cost you your life.


That’s the F that never gets mentioned. People always talk about “Fight or flight” and rarely mention one that happens often, “Freeze”


Lt. Col Dave Grossman has fantastic studies and information on the human brain and how it goes thru the decision making process. He’s changed a lot of my day to day and training habits.