Harbor Freight is a great place to pick up hammers, punches, and anvils. However you get what you pay for when it comes to equipment. Knowing that you are trying to thread typical firearm parts (generally fine-thread), it is going to be tough to keep your runout to a minimum while tring to thread anything with a cheap lathe. Not to mention that the smaller lathes only have a short distance between centers (10" or so), and make it very tough to turn something like a threaded barrel as you mention. The smaller lathes would be perfect for flashiders, with the ability to do mostly hand tapping for an inexperienced individual. My recommendation would be to pick up some machining handbooks, or take a maching course or two at your local technical school or community college.