I think of the Greener crossbolt as cheap last ditch insurance in case of a huge failure in the double underlugs. It could be said that if they do fail, the Greener will probably also fail, but the oldtimers evidently didn't think so or else they would never have gone to the trouble to put them on so many guns. The crossbolt does not have to be an extremely tight fit, it is in my opinion, just there to help keep the gun from opening completely during firing. I have looked at many Greener crossbolts and have even smoked some of them to see how tight they were fitted. I have NEVER found one that even touched the hole through the rib extension, let alone bolted it tightly. Maybe all these guns that I looked at were cheaply made, but if so, that included Berettas, AYA's,and Laurona's. All reportedly, good guns. I don't think they were ever intended to fit tightly, and maybe as some have said, they were only put on there as a sales gimic. It always makes me feel good to know that my guns have them, though.