I have a Remington 870 12ga that has the Bullpup Unlimited conversion installed. The barrel is 18.5". I've fired around 100 slugs through it.
Includes the shotgun, angled foregrip, flashlight, red dot, original laminate furniture, tube extender.
PayPal accepted from long term members.
Have more pictures if there is interest. It's about the size of a 16" AR15 with the stock all the way forward.