Look around a bit here:
I started with the 124 gr. Gold Dot because it was fired from a Glock 26, as I suggest for your vest gun. Note that penetration and expansion are nearly equal to the .45 ACP, with the 200 gr. Gold Dot. Actually, penetration is a bit less, but expansion is MORE.
Use the index on the left side of the page to compare other calibers. Check the 124 gr. Golden Saber:
and see that it actually performed BETTER than .45 ACP. That test was fired with a 4" barrel, as you would have in the Glock 19, which also disappears in a shoulder rig.