Hi,
Your question requires a bit of unpacking. First, if you are not familiar with case hardening and not set up to do it, don't mess with your lock or you may ruin it. I believe any heat treating like case hardening will void warranties such as those offered by Chambers and others. That said, I always case harden my lock plates, flint cocks, pans, and frizzens. I do it because it improves the sparking on my frizzens and prevents the flint cock from peening the bolster of the lock plate. It also enhances corrosion resistance of the plate, flint cock, and pan. However, I know what I am doing and am set up to do it without risking warping the lock plate or ruining the other parts. My regime significantly improves every commercial lock you can buy so I don't worry about any violation of warranties. Nonetheless, if you are not proficient or lack the set up to properly case harden (which requires a forge, or a gas or electric heat treating oven), I suggest not bothering. The commercial lock without heat treating should perform well enough.
dave