I had a Gunsmithing business. Here's what I learned.
1) It won't support a family of 4 as a single income household and send your children to college
2) It's a hobby with income potential
3) Not a bad retirement gig, unfortunately the customers don't understand a retiree's schedule.
4) If you aren't soured with people before you may be afterward.
5) You are making an income from, for the most part, an activity that is essentially a hobby to your clientele (LEOs and PMC/ESDs excluded) so your business model will always be more demanding than your clientele's need for your services (LEOs and PMC/ESDs excluded) . It's not like a Auto Mechanic, Doctor, Teacher, Firefighter, etc.
I'm retired now, I bought another Bridgeport Mill, Cincinnati Lathe for my own use, not to do someone else's work.