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9mm Vs 40 Cal. Here comes the Caliber Debate & Hate


I never got in to .40 S&W when it was popular. I started with .45ACP because I started with a 1911. As I got smarter about ballistics, capacity, and weight I moved from .45ACP to 9mm as a carry gun. Why? Because the Glock 19 is what the friendly shop employee pushed on me. We've all been there.

Hundreds of pistols later I still had never owned a .40 Cal because I simply didn't need one. 9mm was cheaper to shoot and easier to source and if I wanted more power I could grab 10mm, 7.62 Tokarev, etc. Meanwhile .40 Cal had faded almost out of existence with few gun makers producing new models in the caliber. I didn't know if I had missed out or not, but also didn't want yet another caliber to keep inventory of.

That was until a local pawn shop had an early-generation Walther P99. Not the AS model, just a plain-Jane P99. As a Walther guy I had to pick it up. Sliding it out of the greasy nylon holster my eyes bounced from proof stamp to proof stamp as I observed all the little things that made it different from my much-younger P99 AS. Unfortunately one of those differences was the chambering; .40 Cal. I bought the gun anyways and it sat for a few months while I tried to find ammunition for it.


We finally got it to the range and it sparked the old caliber debate. 9mm Vs .40cal. We all know that .40 has more recoil, costs more, and reduces capacity slightly, but do we really know how much more powerful it is? Is it worth the recoil and cost?

With two firearms of the same barrel length, trigger, and feel we could almost fairly compare the two side by side. Hand fitment and trigger control would not be variables between the two guns.


The faults in our test include:

  • ammunition not made by the same company (was our ammo a true representation of each caliber?)

  • Is 115gr the best comparative 9mm load or should we have tried 124gr, what about a 124gr NATO load?

  • Sights are different: during our "management" test this could make a difference.

  • Condition of the recoil assembly: Was the older .40cal gun's recoil spring tired? Is the DPM Systems spring in the 9mm gun a cheat?

We found the answer to some of these, as well as what the difference in muzzle energy was between the two guns.


The biggest surprise was at the end. Teya suggested that although the DPM systems recoil assembly was meant for 9mm, it might make a difference in the .40cal pistol if the .40cal pistol's spring really was worn out. As you saw it made a significant difference.

We've run DPM Systems in ARs and 9mm Walthers where it made a great difference, and in AKs and the Sig P365 where it didn't make a big difference. With this old Walther P99 it was a remarkable difference.

All of that said and done, is 40cal worth it? I think that depends on you. a 20% increase in muzzle energy at the cost of one or two rounds of capacity in a larger pistol may be worth the trade off. Muzzle energy only matters when shots hit, and modern defensive ammunition performs well at the energy it was designed for. As long as you've got enough barrel to get the round up to its intended speed maybe the bullet doesn't matter.


Let us know your thoughts. This could be a spicy one, or maybe everyone has moved on from .40cal?

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7 Comments


Philipp Weimann
Philipp Weimann
Jun 22, 2023

I have both the .40 S&W and 9mm in the exact same gun, both full sized polymer frames with 4.5" barrels and have been shooting the .40 S&W since the '90s. I was told a long time ago to relax my grip and not stiffen it as I was (I'm not going to share the exact words but that's what was conveyed). After putting that into practice my shots have always been in tight groupings and very consistent with my .40 S&W. I've gone to the range (not to boast, that's not my thing), set up my target (the typical person silhouette) at 20 - 40 feet which is what I'd consider a typical defense distance and put my …


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Ronco Vegamatic
Ronco Vegamatic
May 24, 2023

Issued the HKMP40 compact and used it for 12 years. Honestly, I noticed ZERO difference between it and the 9mm. Sold the G19 and bought a G23 (40sw) which ALSO easily and quickly converts to 9mm via KKM precision 9mm barrel. I like rhe extra power of the 40sw and the fact that I have so much issue ammo inventoried. The 40sw HP is literally a "flying ashtray".

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Different strokes for different folks. My first encounter with .40 was my Steyr M40-A1, and need I say more? I'd shot it through other platforms, and funny enough I enjoyed it through my Keltec Sub 2000 Gen 2. And yes, it takes Glock mags lol I know quite a few Staties, and local LEO that still carry their Glock 22's. Well if it ain't broke.....

If yo don't shoot yo footy wid a shorty, you gon miss 🙄 You guys should have shot the spinner with the .40!!

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Mark Miller
Mark Miller
Sep 09, 2021

I can get better hits faster with a 9mm. I am willing to trade a little penetration for performance. The .40 is still a great round if you are into than. 10mm kurz.

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Unknown member
Sep 09, 2021

I prefer the .40 and enjoy shooting it. Gun manufacturers just don’t make very many options in a .40, so My last purchase was a 9mm. If they made the same model in a .40, I would have purchased that instead.

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Replying to

The S&W MP 2.0 handles .40 pretty well.

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