I forgot to mention, it is a 20 gauge. Yes, we measured down to where the barrel end of the barrel is inside the receiver (without taking the barrel off. It hasn't been cut. But the rib is probably a Simmons rib, although it is not stamped Simmons on the side of it. The vented rib has the square posts milled to the barrel and when you look down the muzzle end of the rib, the rib looks like it slides down over the posts. So, I am pretty sure it is a Simmons rib. But, I think it is a special order 24" barrel that came with no rib and was later sent to Simmons to have a rib put on it. It is a nice gun in nice shape. The wood is in nice shape, but is not high grade at all. He is asking $1500.00 for it.
