I was quite disappointed with the  Weber PCC Vise Block once in hand.  I was aware that the block was of wood construction but not foresighted enough to think twice about dimensional stability.
The surface is sanded & painted wood which all by itself requires a hefty vise bite to keep it still with my PCC impaled thereon.  A cut back or some other feature to keep it from slipping or rotating in the vise would have likely avoided necessity to mar the surface to immobilize block and firearm.
The fit is tighter than I expected.  Getting the magazine catch to engage on the block required an amount of force I am not comfortable employing.  At the time I wondered if the block was warped a small amount but never carried through to look.
It was exactly the product I was looking for when ordered but in this case looks far outstrip function.

RE: 
The material is a high density polythene and not wood. I talked to the manufacture and I did add to our description that in most cases the gun will seat onto the block after activating the mag release.  Some forged lowers do not lock however the vise block functions the same.
Sorry the vise did not meet your expectation