I use my lead casting pot for all my tempering, especially with springs but always use a thermometer to make sure the temperature is accurate. You can use a kitchen oven as the instructions say for the internal parts, I have in the past with excellent results but again, verify the temperature with a thermometer, Kitchen ovens can vary widely from what the dial says. Taylor is right, the parts have different recommended tempering times/temperatures. Being an old married man, I always follow directions. Just to throw something else out there, Rifle Shoppe locks use the same steel in their castings and their instructions are completely different. I have used their instructions which are on their website on their lock castings with excellent results. They recommend case hardening most of the internals after a high polish. You might want to just take a look to see if that might be more doable for you