He asked for magazines that have the LRBHO feature, not an actual LRBHO. And there's no need to 'flame' the guy for asking a legit. To the OP, I don't know of any shotgun magazines that will hold open the bolt just Surefire's rifle mags.
I'll flame you before anyone else does in a meaner way....Your Saiga and everyone else in the US.....barring they do not have one of the old Jeric designed LRBHO, one of Cobra's LRBHO (someday available), or another homemade LRBHO are all in the same boat. Since you are a member, then, within a section, you can use the search option and searc