Does not fit, junk tolerances - Firefield Remington 870 Shotgun Saddle Mount

It does not fit 870 Super mag, and the seller should say so. I doubt that it fits any 870. So tight that it severely scratched the receiver. I wanted a mount to use rather than send it back so ground a few thousandth off of the inside of the mount, lubed with gun grease and still used a small mallet. The sides were flared out but was able to pull them in with screws. At least it is tight.