Holding an opponent at bay with your off-hand forearm (while keeping it from slipping in front of your muzzle) can prevent contact between the pistol’s muzzle and your adversary, which could possibly cause a malfunction.
An Official Journal Of The NRA | What Are the Effects of a Contact Shot for Personal Defense?
In your extreme-close-quarters-encounter class, you were cautioned that contact shots could cause a handgun to malfunction, and possibly not fire at all, leading to an even graver situation.
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