In my opinion, the modern 9mm defense loads are even better than .45's. They penetrate just as deep, expand just about as much and you can fit more into a magazine.
Back in the day, the .45 was the thing, but today not so. The modern 9X19 is as or more lethal on a person as any .45 has ever been.

There are 158, 160 and 165gr 9mm bullets out there ..........

The only problem is.........
a little 3.5" 9mm barrel is not going to cut the mustard getting
to the world of the .45 cal. with bullets larger than the 147gr.

Good luck.

The data tables indicate that a 9mm could push a somewhat heavier bullet to 830 fps, which is equal to the .45. If the bullet is built to expand at that velocity (and we know that a 147 grain bullet can expand to 1/2" out of a 9mm) what's to lose?

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"He was kinda funny lookin'"

Modern 9mm are better than they were, but if the proposed bullet would outperform other 9mm rounds in SD situations, why not improve it? Speer now makes a .45 caliber Gold Dot that is better than an fmj ever was. Why not get as close or surpass that with a 9mm if possible.

I keep hearing that no handguns give adequate performance especially compared with a rifle. I'm not going to carry a rifle, so I'd like my carry round to be as efficient as it can be made without adding any more to what you carry than about 20 grains of lead/bullet.

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"He was kinda funny lookin'"