What is a Title 1 Firearm?
Title 1 firearms are long guns (rifles and shotguns), handguns, silencer, and firearm frames or receivers.
Title 1 is generally called the Gun Control Act, (18 U.S.C. sec. 921 et seq.).
Most NFA weapons are also Title 1 firearms.
So it ends up being a "pistol" per GCA.
Pistol. A weapon originally designed, made, and intended to fire a projectile (bullet) from one or more barrels when held in one hand, and having (a) a chamber(s) as an integral part(s) of, or permanently aligned with, the bore(s); and (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).
I bought my 870 strictly for home defense it came with a factory grip
The issue is not with a fore-grip, either factory or after market. It is with the Cruiser types that do not have a rear stock, only a pistol type grip.
The 17" barrel is what is in question.
Remember, this is the group that classified a shoestring to be a machinegun. I got a letter to prove it.