Catalyzes the insertion of Co(2+) into sirohydrochlorin as part of the anaerobic pathway to cobalamin biosynthesis (Potential). Involved in the biosynthesis of the unique nickel-containing tetrapyrrole coenzyme F430, the prosthetic group of methyl-coenzyme M reductase (MCR), which plays a key role in methanogenesis and anaerobic methane oxidation (PubMed:27846569). Catalyzes the insertion of Ni(2+) into sirohydrochlorin to yield Ni-sirohydrochlorin (PubMed:27846569). Co-sirohydrochlorin + 2 H(+) = Co(2+) + sirohydrochlorin 2 H(+) + Ni-sirohydrochlorin = Ni(2+) + sirohydrochlorin Cofactor biosynthesis; adenosylcobalamin biosynthesis; cob(II)yrinate a,c-diamide from sirohydrochlorin (anaerobic route): step 1/10. Homotetramer; dimer of dimers. Belongs to the CbiX family. CbiXS subfamily.