I called Stevens not to much help all she told me it is a 3mm bead
I know this is a low price gun but the manual is very weak, Some things I have found out this week.
You can get extended chokes from TRULOCK for the 12 gauge and maybe others.
The Limbsaver recoil pad that is just about a perfect fit for wood stock is Model 10800
about $32.00 on line.The stock bolt requires a 10MM socket to remove.
Never heard from Stevens/Savage, but I checked with a smith, told me earlier guns were pressed, later threaded. Told me to just give it a twist. It was threaded. 3-56/2.6mm. Put on a fiber optic, used some blue lock-tite.
I don't know the s/n or year of the switch over from press to thread. Mine is new.