Scot,
You and I have been thinking along the same lines. I've been doing some research and have found this website to be very informative:
http://www.mini-lathe.com/Interestingly enough, I learned that the 7x12 is actually 50% longer than the 7x10. The 7x10 is actually a 7x8 if measured the same way the 7x12 is measured. I have eliminated the 7x10 as a possibility for airgun parts. The short length is especially troublesome if you plan to drill into the end of your manufactured piece where the drill bit will take up a large portion of the length.
I am seriously considered the following:
http://www.toolsnow.com/browse.cfm/4,876.htmlThis is the same Chinese lathe sold by many, including Harbor Freight, but includes a better package, including a 5 piece cutting tool kit from Tools Now. All these lathes are manufactured by the Sieg Company in China. Surprisingly enough, the machine shop that I lease some warehouse space from has two older, much larger lathes that are made by Sieg. I am assuming it is the same company.
If you are not in a hurry, Tools Now often has free shipping offers or other discounts. Or they may have a truckload sale coming near you. Expect some sheet metal damage if you have it shipped.
Don't forget to add a couple B3s to your order!!!
I have talked to others here that have these lathes and they are very happy with them. Maybe they will chime in here with some reviews?
Good Luck.