The Choate Tool Mossberg 930 Pistol Stock is not listed as being compatible with the Mossberg 940.
The Choate Tool Mossberg 930 Pistol Stock M-5 will work with that Mossberg 930 SPX.
Yes. The Choate Tool Mossberg 930 Pistol Stock will fit Mossberg 930 and 935 model shotguns. It provides a length of pull of 13.75" and includes the recoil pad with screws.
This is information direct from Choate Tool regarding the spacers, recoil pad and length of pull:
"The MK5 pistol grip stock features our spacer system which comes with one 3/4 spacer included. You can lengthen your stock by simply adding new spacers and longer screws. NOTE- The 930/935 shotguns can not be shortened shorter than 13 3/4 inches because of the recoil spring tube that protrudes form the back of the receiver. Weight- 1 lb. 6oz"
The shortest length this stock can be is 13 3/4 inches, additional spacers can be added to increase length of pull.
No, this is not compatible.
According to Choate, there are no instructions in the package.
According to Choate, yes it will fit the Mossberg 930 Pro.
This stock will not fit the Rock Island pump shotgun.