I know I'm showing my age here. Back in the day we used clout nails to attach keystones an triangles to flats rather than screws or staples. The nails were about 3/8" longer than required to fasten the 1x and the triangles. You place the steel plate on the floor under the joint. When you pound the nails in with a hammer (yes we used hammers) the end of the
nail would curl up when it hit the steel plate. The finished fastener was like a
rivet with the head on one side and the curled up end on the other. It made for a strong joint. If you had a concrete floor you don't necessarily need the steel plate but they work better with the steel. I haven't seen clout nails in 40 years.