Yep, I was getting ready to look in the bolt bin for a shorter one when I thought, what the heck, look at the instructions.
Overall I was pleased with the Mesa adapter, I got mine for a fairly good price from these guys:
https://www.mountsplus.com/mesa-tact...ngton-870.html
Right now I'm on the look out for a good sporter length forearm that wont cost me an arm and a leg. Eventually, I'll SBS this, but it is 3rd in line for stamp money. Until then, I plan to soothe my inner Phil Singleton and use it sling supported CQB-style, the short forearm doesn't let me adjust the sling like I prefer.
Gee, it's great to have a new toy!