(Wiping coffee off monitor)...
Sonny, that made my morning, thanks.
Got to thinking about this last night, so I pulled on Kevlar, grabbed the 870YE with its 13" pull,made sure it was empty and tried some mounts. Then repeated with Frankenstein, LOP about 14 3/4". The YE was a little easier to get right. The two "Serious" 870s here fall in between at 14 -14 1/4".
I'd rather have a stock a little short than too long. This Hogue cadet stock should be close to ideal in length for "Serious" use for many folks, and doable in armor or winter duds....