If you chamber them in a proven cartridge that is known to shoot well across a variety of rifle makes then your idea is entirely possible. If you choose a finicky one off cartridge your odds will decline of finding a sweet spot that performs in all the barrels.
I am on my 4th 6 Dasher barrel without doing load work up and excellent results on all of them with the same load. I chamber my own barrels with the same reamer. I changed contours and twist rates and all the barrels still shot the same loads plenty good for my standards. This may be more a testament to the forgiveness of the 105 Hybrid bullet and the 6 Dasher cartridge.
All of these barrels will generally shoot .3 to .5 MOA.
Depends on who makes your barrel.
For instance, ER Shaw buys the steel for their barrels by the HEAT, so all of the barrels in that lot have steel with identical composition. There are still variables to consider, like the condition of the cutter or button used, etc...
If you can find a high end barrel maker that can guarantee that the barrels came from the same HEAT, you'll be part way there.
As stated previously, use your own reamer, possibly invest in a rougher and a finish so your finish reamer will keep it's dimensions longer.
Or, just do a load work up for each barrel. You may luck out.
In theory, yes. In practice, no. When barrels are profiled, one can be a bees-dick thicker or thinner on diameter. One chamber will be a hair deeper or shallower than the next, the rifling will be slightly different shape between each. The purity of coolant while cutting may introduce particles, etc. Everything "adds up". Many people can't tell the difference, but top end bench / fclass / PRS shooters will. Also be aware you would have to shoot your barrels equally so they all wear at the same rate, and clean at the same interval.
What would happen if you shoot one in winter, and one in summer. It's down to load consistency, how hot / cool the barrel is, etc.
Short version: too many variables to control unless you machine them in a NASA grade lab and shoot in temperature controlled indoor tunnels.
I shoot the same loads in winter and summer, and charge weights between two barrels are also very close. When I get a new barrel I do a ten shot pressure test, then go back to old charge weight and run OAL test. If the pressure test doesn't change. I have changed loads more for different lots of powder and different kinds of brass, more than different barrels. I would hate to guess how many 223s I have seen shoot lights out with 26.4-26.6 of Varget and any 55g bullet I have. 23.6 or so of 8208 with a 77.
In theory, yes. In reality no. A barrel tuner would likely solve that problem though. I believe someone makes a barrel tuner that also can allow for a muzzle brake to be used. Can't remember who off the top of my head.
Those of you who are into extreme long-range shooting have probably heard about the tacomHQ Structured Barrels because apparently, these barrels have been around for at least a couple of years. In a nutshell, these are bull profile barrels with eight holes drilled around and along the bore.