Late last year I experimented with 175gr Silvertips from a stock G20 and really wasn't impressed. My goal is to have as much of an energy dump/expansion with full penetration that won't go into the next county.
Just for fun I chronographed some 210gr Silvertips from a .44 mag and may have achieved that goal. In recovering 3 of the 4 rounds recovered; expansion measured between .96" to 1.106" which is very impressive from a .429 bullet. The fourth round expanded to .706" and spun off a shard of lead approximately .25" wide and 1.07" long. This was not from a full boogy load, chrono was over 1550fps which equates to about 1150ftlbs of energy.
180gr in .40 cal is relatively close in sectional density to 210grs in .429 cal.; 140grs in .357 and 230grs in .451 cal.
Using three different powders it was very easy to run 180gr Golden Sabers from a 6" KKM barrel from 1280fps (600ftlbs) to 1370fps (750ftlbs) and these bullets penetrated and expanded better than I was able to get several months ago from a stock G20 (combination sheet metal and/or sand and/or wood).
I expect 175gr Silvertips in 10mm to at least equal the 180gr GS bullet's velocity and leave a golf ball sized hole thru a BG and not penetrate the first layer of sheet rock in a room. This of course is supposition on my part, but the Silvertips are very explosive in their expansion, they tend to hold together and the velocity/energy from a 10mm should be enough to push a .90" bullet through a BG and expend itself upon hitting another barrier.
The Strasburg Papers give a different quantitative slant to what Fackler published; but they agree that .451 230gr FMJ is the smallest ball ammo that should be used for self defense and also the need for multiple shots on the bad guy.
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- General George S. Patton, Jr
"Speed is fine, but accuracy is final - Bill Jordan