It's also important to note that .380 ACP was substantially downloaded for decades due to the popularity of cheaply made blowback .380 Pistols which were frankly unsafe to shoot regular loads through, so ammo companies started loading their ammo below Standard Pressure to avoid the possibility of any legal action taken against them because some guy's Saturday Night Special/Ring of Fire pistol catastrophically failed and injured him.

Once the trend of modern, locked breach .380 Pocket Pistols took off, ammo companies started loading ammo to the proper specs again, with some companies loading their ammo right to the edge of SAAMI Specs because the locked breach design can handle much higher pressures than straight blowback.

So in other words, if the guy who did these milk jug tests did so before, I dunno, 2010, then yeah, it's not too hard to believe that .380 ACP FMJ of that era didn't penetrate very well.

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Shooting Comfort is bilateral.