If .10" bullet diameter doesn't matter it follows that the .25 ACP should be every bit as effective as a 9mm.

Since this isn't the case, there has to something else at work.  I propose that it is logarithmic scale based on the contact face of the expanded bullet.

My view of the whole thing about FBI change, is that if it ain't broke, don't fix it.  I'm not aware of any valid reason to go back to 9mm and consider the data they employed to be marginal at best.

The FBI's decision to move away from the 10mm was the end of them using the valid reasons in their sidearm decisions.  Maybe sooner.

And I am not being the 10mm douche here.  It was the right decision.  They were already shooting 40 S&W loads, just from 10mm cartridges.  But they used the excuse that excessive recoil was the issue.  Lets see...Same bullet, same velocity, smaller lighter gun.  That is more recoil, not less.

If you made a twenty-five caliber round that pushed a bullet the same weight and velocity as a 9mm, then it'd perform about the same.

I bet a 125 grain .251 bullet at 1200 fps would penetrate worlds farther than a 9mm 125 at the same speed.  You would need a 250 grain 9mm bullet to get the same sectional density.  A 62 grain JHP "25 Super" running 1300 fps would give you a pretty fair comparison.

Terminal ballistics are weird. We've got a few rules of thumb that have limited application and that's about as scientific as we've managed to be.

Imagine two projectiles. Both travel 300 fps (fairly slow by firearm standards). One weighs 620 grains, the other 400. Both are routinely fired at living targets. What effects does each have?

Spoiler (click to show/hide)

The heavier one is a 12 gauge less-lethal beanbag round, the lighter is a broadhead arrow suitable for hunting most game in North America.

But the bean bag isn't sharp  .

Neither are most handgun rounds. And if they were they probably wouldn't work quite as well.

s___'s a lot more complicated than mass and velocity.

That's what she said!
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I wonder how a "pointier" edge would effect a handgun round  . Surely someone has tried it before.

We have tried the pointier edge.  On NATO 9mm ball.  Which goes through like an icepick, making SMALLER than 9mm wound channels in elastic stuff like human meat.

Improved armor penetration traded for reduced wounding performance.

That's a wadcutter, or maybe a hollowpoint that doesn't expand. It makes a nice hole the diameter of the meplat and definitely works better than a round nose.

I shot a javelina once with a 9mm 147gr Winchester White Box JHP. Judging by the wound channel and the complete penetration, it didn't expand. It did make a nice hole that bored straight through a lung, the liver, and the spine. Piggy was dead right there.

That's actually really impressive. To my understanding, Javelinas can be quite resilient. Either the marksman was very skilled, or that's a round design you could even trust to bring down squirrel  .

Flat meplat rounds stop animals far better than they should for their weight and size in my experience.

I assume it may use secondary material to increase the damage, OR maybe it doesn't let vital components 'slide' out of the way on its trajectory through the body.

I just know that Elmer Keith guy might have been on to something with non-expanding projectiles at typical handgun velocities.

  Did someone say Wide Flat Meat Plate?

 

Oh. Emm. Gee.

I used to have to make that exact tray (or else pretty dang close) back when I worked at the supermarket.

Oh. Emm. Gee.

I used to have to make that exact tray (or else pretty dang close) back when I worked at the supermarket.

Were they as good as they look? That thing looks delicious .

All this internet talk has brought out an unknown hipster part of me. I want to buy another 40 cal. Might just make it an HK and make some forums howl


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The part about making it an H unt K was too far...

Well, he has to do SOMETHING with all the money he's saved on those two Ruger revolvers, no?   

Man, it's a funny feeling, but some days I wake up and wish I just had heaps of money  .

If you really think about it, and are honest, that "some days" should probably be "every day".