If you own one of those factory Remington 870 top folding "for law enforcement use" stocks, could you please help me with two questions?

1. How much of the barrel does the stock buttplate cover when folded when you measure from the front end of the receiver? I'm pondering a SBS project, and I want to have maybe half an inch of barrel in front of the stock buttplate when it's folded.

2. Will the stock fold properly on a vent rib barrel or will it only work on a barrel without a rib?

Thanks!

On my 12" barreled 870 it sits right even with the end of the hand guard.

I had to take a file to the rear of the stock where it locks up to get positive "lock" using a vent rib barrel. It isn't necessary unless you're a perfectionist though. Mine locked and stayed in place before just fine the button just didn't protrude all the way out like it should have.