Beretta AL391 with Benelli M4 stock

[jaybird888]

Looking for some input on my Beretta 391. I noticed on Beretta web page they have a Benellli M4 pistol grip stock offered in the parts and accessories for semi shotguns. I'm wondering if its interchangeable with my Beretta 391...
Any help??

 

[fijit]

hi just wondering witch is better m4 or m2 for accessories