Honestly, at first glance I would not have known the VFG turned that gun into a violation. I thought it was ugly as heck, but had no idea it was a violation.

Add this to the list of things I've learned here on SF.

Yep. Adding a vertical foregrip to a handgun creates an "Any Other Weapon" that's subject to NFA laws, thus requiring registration and a $200 tax stamp.

Not usually an issue, since most folks (besides this dummy) wouldn't bother to put a VFG on a handgun anyway.

However, it's more likely to be an issue nowadays due to the proliferation of "rifle-like pistols", such as AR pistols with arm braces. VFGs are a no-go on even those, since they're technically pistols, although angled foregrips and hand stops are okay on pistols like that.

The only way to legally put a VFG on a pistol without a tax stamp is if it has an overall length of over 26 inches, which skirts the AOW rules. AOWs have to be "concealable", and a firearm that's over 26" in length isn't considered concealable. You sometimes see VFGs on stuff like AR pistols with 11.5" barrels, which have a 26"+ OAL.