I put a spring from a ball point pen in my Caps Lock once. (Using Cherry MX Browns) I didn't measure how much force it took to press it down, but I would think it was well over a kilogram.
First time I pressed it I thought it wasn't going to budge, but sure enough I just really needed to lean on it. It did the job of preventing any accidental presses, but I thought maybe it did too good of a job.
I ended up using an MX Gray in my Caps Lock and an MX Clear on my space bar. I don't like the Gray switch in my space bar. It should be much lighter than that, IMO.