You need to have a choke in the barrel to shoot your gun. If not you'll **** up the threads in the end of the barrel,and you won't be able to use the chokes anymore.

I've only shot slugs in my 870 a couple times,both times I used the I/C (Improved Cylinder) choke based Remingtons reccomendation.

If it doesn't specify in your manual,I'd contact Stoeger to be sure.