Are you planning on doing production runs ? If you are going to make the same part 10,000 times, CNC is awesome. For job-shop type gunsmithing work, not so much.
As far as retrofitting older lathes, speed is your friend. There are some very good reasons why CNC lathes with carbide tooling run at spindle speeds that would make most older manual machines hop around the shop floor if not rip themselves apart...
Personally I have found the perfect combo to be a heavy, rigid machine with a DRO
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