I think you may be boxing yourself into a corner for a sometime job. Big machines are just plane slower to use on small work. Barrels for actions like a Rem 700 dont need a big machine.
The specs on the Arca electronic threading lathe show a 1.25" hole through spindle. Earlier this week I chambered a 1.35" shank barrel, and tomorrow and I doing a 1.25" shank barrel. Most of the barrels we do are 1.25" diameter shanks.
If it had 1 9/16" spindle it might be a good fit. I can always do the big stuff in the 1440 GT.
We also have two competing ideas. If I were making the call it would be a tricked out 13x40 or 14x40, or even possibly a CNC machine. However, there is a big push for a 17" manual lathe because that is what a couple machinists/manufacturers have and like.
I don't like big machines because of all the bushings needed and the general hassle of chambering. I really like my inboard and outboard spiders and short headstock. However. these bigger lathe guys can go from blank to chambered barrel twice as fast as I can, and their end product specs out as good as mine. So I don't have as good of case to make as they do.
To be honest, I don't think it's in the dial in where they beat me. I can get most barrels dialed in to under .0002 at the throat around .0002 at the breech in 10 minutes or less with the Interapid long reach.
Where I am slow is how I double check everything and make multiple light passes.
I take .050" for the first 2-3 passes on the tenon, and I like my last past to be within .010". That minimizes deflection and keeps the diameter consistent. When threading I use the compound only. I make .005" cuts until .030, then .003 to .048, the .002 or .001 after that. I clean the chips off after each pass.
When chambering, with a flush, I go in .100 at a time at first then .050, pulling the reamer back so the flush clears the chips. I do that to about .300 to go, then I pull the flush, patch out the oil, and scope the bore to make sure everything looks okay. Then I hook everything back up and go to within .020 to 030", pull the flush, patch out the bore and scope again. I then measure with a feeler gauge between the shoulder and action and add .002 (.002 for a sandwiched lug), zero the tailstock, and make my final cut.
These other guys chamber in one shot. I am sure they make bigger cuts in both turnings and threading, and don't check their measurements as much as I do.
