wow6599, I'm sorry if that sounded snarky. I didn't mean it that way at all.
RKPulliam, This isn't intended to be a comparison. You're right that 10mm and .357 mag are very similar but 9x18mm is a completely different animal. These are just the loads I tested last week. Take a look at my channel, and you'll see a lot more tests, mostly 10mm. I collect the data and report it without bias. I generally offer no comments in the description of the video unless some clarification is necessary.
Most 155 gr .40 S&W is lead core and can be safely driven to much higher velocity than a 155 gr all copper bullet. While this bullet could probably be pushed faster in 10mm, you'd be hard pressed to get even this much out of .40 S&W because you'd be running out of case capacity. As I noted above, the 155 gr TAC-XP is a tenth of an inch longer than a 200 gr XTP. I haven't measured the C.O.P. but it is certainly comparable.
As for potency, I'm sure you probably just meant that 10mm is capable of higher velocity for a given projectile weight and that's true. 10mm has a greater case capacity and higher SAAMI spec pressure limit. Lot's of folks think that more energy or more velocity automatically means more effect on the target but that's not necessarily true, especially with handgun cartridges. According to Dr. Fackler and Dr. Roberts, typical handgun bullets (including .357 and 10mm) don't move fast enough for the temporary stretch cavity to be a significant wounding mechanism. That means that the only factors that substantively contribute to wounding are width of the permanent cavity (directly proportional to expanded projectile diameter) and penetration. That means that 10mm is generally not capable of producing significantly larger wounds on human targets.
Like .357, though, it really comes into its own for woods defense. You can have your cake and eat it too, so to speak. You can use a projectile that expands but still penetrates deeply enough to be useful for large animal defense (200 gr XTP at 1,200 fps) or you can carry a magazine of people defense ammo and a magazine of critter defense ammo. Of course, the cost is recoil but you can still purchase "FBI lite" style commercial ammo, which is every bit as effective on humans or load it yourself.
In my opinion, the real strength of 10mm is versatility.
