RE: I want to build a 358-STA tell me what I need to do?
Hold on now....this is a wildcat and strictly a custom build....and it's going to be a little costly.
BTW, Winchester did chamber for it in their custom shop...maybe still do...check it out!
Forget about reboring an existing barrel....new barrels are the same price (almost) as rebored barrels.
You need an action.....any of Remingtons long magnum actions will do for this. Remingtons 7MM Rem Mag action is much longer than Winchesters and will actually hold and feed the .358 STA.
Any action currently sporting a .375 H&H, 8MM Rem Mag, 300 WBY mag, .340 WBY Mag, .458 Lott, or any of the long Remington Ultra Mags will do. I recommend you procure a Montana 1999 action for the job. (about $450)
Call your favorite barrel company...Douglas, Shilen, Hart, Lilja, Krieger, Pac-Nor, others and ask for a "FTC" barrel in .358 STA chambering....choose stainless or chrome moly. about ($275)
Get a stock from McMillan or Borden's Rimrock....(about $375) ( A wood stock finished and checkered will be well over $1,000)
Find a metalsmith to fit the action to the barrel...about $100 and blue it another $90...
Glass bed or pillar bed the Barreled action to the stock....about $75
Install scope mounts and a scope....you name the price....and if you want iron sights...add another $100
Ways to save a few bucks:.....Find a used Remington long action magnum....rebarrel it to .358 STA and have it installed on the existing old stock. savings is about $500
Buy your new barrel in stainless so that you don't have to reblue...savings is about $40
It's very unlikely that unless you can do much of the work yourself that the tab will be under $800 and that's not including scope or iron sights.
Anything else?