I very much doubt that the No1 action is any stronger than the early made actions, for a start it is made in the cheapest way possible, a lost wax casting, which can never be as strong as a forging given the better grain structure, but the fact that it is both very cheap, and available, is why so many choose to "hot rod" these actions, thankfully, not many people are willing to destry a Farquhason costing Ł5000, to build some modern whizz bang caliber rifle, the Italian Sharps and Winchester copies are all made on very strong forged actions, so must be up to most rimmed calibers, the firing pin size being a limiting factor, but as for the "old" Farquharson actions I have .577NE and 475 No2 NE ,as well as .303" that have done 120 years of hard service in Africa and India none of them showing any sign of loosening up. The lost wax (investment casting) is sufficient as has been proven in service, and I think the American made copies choose this method for cheapness, but I am sure they are all strong enough, there should be very little cut out for any rimmed caliber, the problem comes when rimless calibers are used, there is certainly more recoil bearing surface on a falling block action than there is on a bolt action rifle.