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?