Find my screw

[chucketn]

I am trying to figure out insert tooling. After seeing a flycutter set up with a round indexable insert tool, I decided to try one. I ordered the tool and inserts from CTC Tools, probably my first mistake. Second was not ordering them both at the same time. I ordered the tool, and immediately realized I’d forgotten the inserts. An E-mail to CTC asking to add the inserts to the order was ignored. So, tool came w/o inserts, but hat a Torx screw and tool. I tried to find the inserts at an affordable price elsewhere, but failed. I later ordered the recommended inserts for the tool from CTC. Second mistake! Inserts came. But no screw. And to pour salt on my wound, the screw that came with the tool falls straight through the hole in the round insert!
So, my question, how do you figure out what is the proper screw for this insert on this tool? Neither description of the insert or the tool on CTC’s website gives the spec for the correct screw. The insert description gives a screw part # that isn’t found anywhere… CTC doesn’t list it, nor does the insert manufacturer. HELP!
Can I just take the screw that fits (threadwise) the tool holder and an insert to Fastenal and expect to find a SHCS that will work?
Chuck