RTI sent me some of the M7 grub screws, they were steel. Easy to drill out, file, manipulate etc. Got a selection of transfer ports from 1.6 mm to 3 mm. I also have a brass M7 TP, delivered will my P1. So RTI use brass and steel. Interesting testing, 😉. Lately I'm mainly using a 3 mm TP. .177...