Both the rifles and pistols are supplied in Poser .pp2 format in a Poser runtime props directory.
However, with regard to DS files, the rifles and pistols are handled differently.
The RIFLES prop directory contains .dsa scripts alongside the pp2 files, so when you load the rifle pp2 in DS, the DS materials are applied for you.
The PISTOLS prop directory only contains the Poser files, so when you load the pistols in DS they load with the Poser material settings. But there is a separate DS content props directory for the pistols that contain DS .dsa material files for the pistols.
So, you load both rifles and pistols from the Poser format props folder. But whereas the rifles load with DS settings, for the pistols, after loading them from the Poser format props directory you have to go to the DS format content directory, select the pistol in the scene and apply the DS material to it as a separate action.
It is a bit of a dog’s dinner, and the pistols really should be updated to have DS-material-loading scripts alongside the pp2 files like the rifles do.