Fletch
Smash Master
You don't need to test this again, I'm telling you all it does is reduce the visual recoil between shots, but since it centers before you can shoot again anyways, it doesn't matter whatsoever. Extended mags is the only good attachment for the SPAS since FMJ is glitched.
Conclusion: There is no defined point that the grip improves nor hinders the spread of the SPAS-11. Further possible tests will be executed in the future.