Grizzly 870 Magazine Cap Threads?

[bc6]

I am trying to design a new Magazine Cap for my Dominon Arms grizzly pump. Does anyone know what threads those are? Has anyone tried the Dlask 870 magazine caps on their grizzlies or a grizzly cap on a 870? I have spoken with someone at Dlask and he heard that one will work on both but he couldn’t remember which one. Any help would be appreciated.
Thanks
Neil

 

[rattle]

Not sure of thread pitch is but I got two of the happy caps from dave's surplus. Both the ones from dave's fit my grizzly and remington 870. Both stock ones were interchangable.

 

[bc6]

thanks rattle.