I have a Mesa Tactical Gen 2 telescoping stock adapter for REM V3 I ordered for my Tac 13. (12GA) Unopened Part #95830. You will need to add your buffer tube, the part didn't come with one. These are almost impossible to find and will turn your V3 into a SBS where legal in your state. 

Know your laws in your state. Shipping not included and at the actual cost. Cashiers check, I don't have the ability to take credit cards.