I 've been pondering exactly the same questions myself. The only difference is that I am a machinist, its what I do everyday for a living, and I have made several guns from "scratch". I have access to a fully equipped machine shop owned by a friend of mine and he lets me use it as I see fit.
I have some of the best equipment made as related to machine tools where I work, unfortunately it's at a nuclear plant and making gun realted items is a definate no-no. I suppose I am a bit spoiled with the high dollar tools, and I get most of the catolgues for tools and associated times at work.
With that being said, I'll tell you what I'm about to get and the reasons why.
Im starting out with a 14 x40 " lathe. The 40" lenth should be able do any decent sized lenth of barrel. One could make do with a 36" but remember that the tailstock takes up a bit of that space.As previously stated , a definate plus would be a center hole of at least 2.5 inches, but these are not easy to find. With the hole that big, one could chuck a barrelled action without having to remove the barrell, in some cases making a project easier and quicker.
Another thing would be a variable speed control. This helps with harmonics as going to a slower speed or a quicker speed on your RPMS will usally eliminate chatter.
Generally, anything over about a 2 horspower lathe is going to require 3 phase power. Although an added expense, I'll probably go with just for the extra power it provides. Some lathes wont go in reverse without 3 phase power.
As for the tool post, I d go with one of the quick change varietys,
and stock up on the indexable carbide cutters and tool holders.
Also, a digital readout is the only way to go.
The milling machine...a definate must have for the serious gunsmith. I'm going with a Series 1 Bridgeport with power feed on all axis'. Im getting the hydraulic quick change tool bar feature, but like I said, I'm, spoiled. Most of the other bridgeport stlye machines are ok, and Bridgeports are a bit more expensive than some of their take-offs. One must have the digital readout on this machine, if you can only afford one readout, I would put it on the milling machine. For porting barrells or drilling and tapping scope mounts, you will have less than an .0005 error with most readouts. For porting , it will make your time much less and you will have professional results . I have seen a few examples of porting , and one hole that is off 15 thousands or so is noticable and will trash out the whole look.
If one wants to build guns than one would need an indexing head. It also helps to do various styles of porting. One just chucks up the whole action and spins the whole assembly in the chuck. It is a must for accurate results.
A drill press would be good for many jobs not requiring a miiling machine and would be quicker to set up. Another must is a pedestal grinder and for shaping of parts and a disk sander is a definate asset.
Another thing to remember is that a machine tool , if taken care of properly will long outlast you. It is better to get the best machine that you can afford, because in this trade you get what you pay for. If your gonna use it for 50 years or so, why not get the best ?
Something to remember is that one needs a good source and understanding of heat treating. A friend of mine is a professional knifesmith and I use his computer controlled furnace for the actions and other parts that need treating.This must be done correctly to prevent catastrophic failures from occuring, along with the laiblity that comes with it if something that you make fails and hurts somebody.
One can jump into gunsmithing as deep as he wants to. It is a fact that good gunsmith are getting harder and harder to find ,not many youngsters are picking up the trade. It can be very rewarding both financially and mentally.
