Hard to say what the Marcospecialties bolt is made of. It looks to be hardened steel, just by the color. If that's the case, it would be stronger than stainless steel. I would not use stainless steel. It tends to seize up or gall, and then you are definitely looking at having to cut it off. I would use hardened carbon steel allen head bolts for flipper rebuilds.

Socket head cap screws are not grade designated as are hex head cap screws. A standard inch series socket head cap screw is 20% stronger than a Grade 8 hex head cap screw and 50% stronger than a Grade 5 hex cap screw.

yes

Try searching socket head cap screw. Many websites. Here's link to Grainger for one. Also a chart showing the tensile strength of common sizes, alloy steel and stainless. Don't buy the stainless. Buy the alloy.

https://www.grainger.com/search/fasteners/bolts-screws/socket-head-cap-screws?filters=webParentSkuKey&searchQuery=partial+thread+screw&webParentSkuKey=WP14420580%7CWP14420583&sst=4&tv_optin=true

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