9mm vs 45 ACP: Why I Will Make the Switch from 45 ACP to 9mm

All day every day I carry a gun. I carry a gun for one simple reason. I want to have the tools available to deal with a life and death situation when the need arises. 

I spend a good bit of time and energy being the best defensive shooter that I can be and part of the equation is making sure I have the right equipment for the job and the right equipment for me to complete the task that requires me to deploy my defensive handgun.

I continually evaluate my carry system and the context of its use to see if I can fine tune it to perform better.

This is always something that can be tweaked to make the system work better in one way or another and considering these tweaks can be a daunting task as often improvement in one area is a sacrifice in another.

Today we are going to look at some of the factors that I considered carefully in my decision to dump the big powerful .45 ACP for the 9mm.

The Preferred Defensive Pistol

When I began teaching defensive handgun courses several years ago, and for quite some time before I was teaching in an official capacity I was recommending, high capacity, striker fired, automatics for anyone who was interested in a defensive handgun.

My typical recommendation was .40 S&W when I started teaching, but as I started to look more realistically at why I was such a fan of the .40 I realized that I was leading myself and others astray due to my competitive background.

I liked the .40 because it made major which has no bearing whatsoever on defensive shooting.  

You see, I failed in that I let some other discipline influence firearm choice. When it comes to defensive handguns, we cannot allow anything that is not related to defensive shooting influence our decision.  

Competition is NOT defensive shooting. My error. I corrected it as soon as I realized there was an issue.

You can read more about my thoughts about 40 Smith and Wesson here.

This has been an issue that I have been modifying my position as my knowledge has increased.  

As soon as I dumped the .40, I made the switch to the .45.  I enjoyed the recoil of the 45 ACP more than the .4o S&W and the terminal ballistics were certainly superior to a 9mm. 

Add to all that the fact that I am a pretty solid defensive shooter and I felt that I was able to handle the recoil of the .45 more efficiently than my average student…

Why switch from 45 ACP to 9mm?

That line of thinking began to unravel almost immediately.  A couple of weeks ago I sat in an ICE Training IDC and finally faced that facts that I knew were on the horizon.  I decided that it was time to bite the bullet and make another change.  Here is why:

Ammunition Capacity

Ammunition capacity 16 rounds in a compact grip 9mm compared to 11 rounds in the .45.  Less conjecture here but this reduces the likely hood of an emergency reload should the round count of a fight exceed what is deemed typical.  Unlikely, yes, but nonetheless a consideration.

When we add the size of the handgun to the equation it makes that capacity issue more of a compelling issue for some people. That 9mm handgun with a higher capacity is smaller overall and most importantly in the grip than the lower capacity .45.  This can be a decision making point all on its own as we want our combative handguns to fit.

Ammunition Cost

  • No comparison between .45 and 9mm.
  • As of today 1000 rounds of .45 ACP is selling for 35% more than 1000 rounds of 9mm.
  • I will be able to train more and use my time more efficiently if I switch from 45 ACP to 9mm.
  • When I think about reloading the same cos ratio exists.  I can save money by loading .45.  But, I can send even more rounds down range if I load the 9mm which I am ready to do.
  • Logistically easier to stock and move large amounts of ammo.

Wounding Capacity

This 9mm, 147 grain Federal HST slug was pulled from ballistic gel after it penetrated more than 14″. Notice the diameter.

This 9mm, 147 grain Federal HST slug was pulled from ballistic gel after it penetrated more than 14″. Notice the diameter.

Lets look at some of the important points of wounding capacity that we must understand.  Wounding capacity is really the ultimate reason to switch from 45 ACP to 9mm.

  • Most people look at the terminal ballistics of ONE 9mm round and compare it to ONE whatever round and use this as definitive evidence as to why one round is superior to another.
    If I only had one shot? But I don’t only have one shot.  I carry a standard capacity automatic. The terminal ballistics of EVERY round that is combat accurate matters not just the performance of a single round in gelatin.
    My rate of fire with a 9mm is significantly faster than with a 45.  5 holes with a 9mm quite possibly trumps 3 holes with a .45 in the same time span in just about every situation.
    Of course these numbers are a matter of speculation but I think we can agree that rate of fire is increased not just for me, but for nearly everyone when we switch from a .45 to a 9mm.
  • Some folks out there have criticized instructors for making the change to 9mm so that the instructor can impress the student with faster demos in class.
    I suppose some folks may make the change for that reason.  The “impress the students” part is the problem there, the shoot faster is the right reason in the first place.
  • In most situations the wounds generated by .38 – .45 are not discernible by ME’s by entry wound, exit wound or wound cavity.
  • If the wounding capacity of individual rounds is about equal between calibers then more rounds in the threat give us much more wounding capacity.

Integrity with students

  • A 9mm striker fired pistol is virtually universally my suggestion for students for a self-defense pistol.
  • I cannot with good conscience recommend a 9mm for someone else and be the exception to the rule.
  • If the .45 were that much better, I would instead drive toward more training for students to handle the recoil of the .45 and be able to shoot faster, but I don’t believe that the .45 is markedly better especially when we consider volume of fire.
  • In addition, with few exceptions students will not put in the time needed to train to be good with the .45.  Students already have resource issues why complicate the problem with a considerably more expensive round that does not have a considerably better track record.


I love the .45 and really want to keep shooting it.  I started my competition shooting with .45’s and so the round is a nostalgic round for me.  I will probably load up the remainder of my ammo and continue to shoot the .45 for fun.  In addition, I will likely stage the guns in my home as defensive guns, but they won’t be my primary defensive tools when i make the switch from 45 ACP to 9mm.

In the near future you will hear an episode about my new 9mm defensive pistols.

I have to say again that this decision was not an easy one.  I have had to deal with a good number of my own personal biases and think critically instead of emotionally.

The benefit of doing this work is refining a system that will be at its prime when the need arises for me to defend my life or the lives of those that I love.  

That is really the purpose.  It isn’t about competition, or looking cool in front of my students, or about my ego.

Those are the issues that we need to set aside when we are preparing for defensive pistol use.  That is what I have worked to do and will continue to do as I progress.  Progression isn’t something I plan on stopping.  You owe it to yourself and to those you love to do the same.  

Consider making the switch from 45 ACP to 9mm.

Originally written by PaulCarlson

4 thoughts on “9mm vs 45 ACP: Why I Will Make the Switch from 45 ACP to 9mm”

  1. My glock 21 .45 with pierce +2 \’holds 15+1 in the chamber. You obviously fail to realize that there ARE several high capacity .45 handguns on the market. Contrary to what you think, many times, one shot IS all you may get. 9mm is for people who dont shoot accurately so they need more rounds and as you stated are too cheap to afford a
    45 round. Is saving a few pennies worth more than your life? Let me put this in laymen terms so you can understand why the .45 is better. Would you rather get hit in the chest with a carpenters hammer or a sledge hammer?

    • How can you say:

      > 9mm is for people who dont shoot accurately so they need more rounds

      … when you just explained that you need more rounds, too?

      > carpenters hammer or a sledge hammer?

      Neither. Both can easily kill you. But a more accurate analogy would be a bigger sledge hammer vs a smaller sledge hammer.

  2. 9mm sucks 45 acp rules and10mm kicks ass too, my uncle in the war was shot 57 times with a 9mm for not bein able to read, well. he lived, but he still cant read.


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