I know AFGs are but what about hand stops in particular the midwest industries grip panel with built in stop. I see lots of ARs with them in the pic thread but they all appear to be over 26'' OAL.

Hand Stops are fine on Pistols of ANY Length.

VFG (Vertical Fore Grips) are what you need to worry about.

Yep, totally legal.  No length requirements.

I believe I read somewhere on here that anything over 2" in length can be considered a vertical forgrip.

I'm fairly sure that's not true...AFGs are not considered vertical grips IIRC,  and they are well over 2" long.

Do you mean 2 inch length perpendicular to the handguard/rail?

I'm pretty sure that's what he meant.

Corect me if I'm wrong, but the ATF is going by hwat they're meant to be, correct?

Ergo,  if it's sold as a VFG, and not an AFG or handstop, then it's a VFG, correct?

I don't recall seeing a letter from the ATF with a specific definition of a VFG.

There is no such thing legally as a vertical grip.  Vertical grip is not defined by any statute even though the Justice Department uses that term.

The correct term is "short stock at an angle to the bore" of which you can only have one on a pistol (unless, of course, you fight their argument in court, then you can have at least two on a "pistol").  

(b) a short stock designed to be gripped by one hand and at an angle to and extending below the line of the bore(s).

Of course, we really don't know if you can have two stocks on a pistol, because no one has asked the question correctly.  You'd think at some point someone willing to publish a properly constructed letter would figure it out, but perhaps those who have just aren't sharing.

https://www.atf.gov/press/releases/2006/04/041006-openletter-nfa-adding-vertical-fore-grip.html