Gentlemen,
First, too funny on the hot apple pie!
We considered doing the vertical grip in a Philly Cheesesteak Sandwich container, etc.....
Seriously(?), our BG-16 grip hasn't changed since day 1, with the exception of the binary texture.
The gap is caused by the grip pocket/etc. being machined a little low on the lower receiver.
Lower receivers begin life as forged ingots with the compound curves already in place. They are placed in a machining center and receive the magwell broach first, with all other cuts indexing off that. The placement of the ingot in the center can vary a small degree, as they are a forged(not machined) form. That's why there is a small difference from receiver to receiver. The relationship of all the cuts stay true to each other, but 'wander' together slightly on each ingot. Hence some have a gap, others don't. That's also why the 'step' on some backstraps, and not on others. We designed the grip to be flush or hang off slightly, instead of the receiver hanging over, which is a sharp metallic edge.
Hope this helps!
Jeff