First, I would agree that shooting from a clean barrel will give a different POI than a fouled barrel. Especially if you are cleaning out all the copper. My Axis barrel has needed a lot of smoothing to get consistently good groups. I also do not clean the copper out of it anymore until the accuracy goes to pot. Then I clean out the copper. At the range I run a dry patch to soak up any oil left in the bore and then about 10 or 20 rounds before it settles down again. Then I only clean out the powder fouling between shooting sessions (50-100rnds per session). I still run a dry patch and take a fouling shot each time I go to the range.

If you are going to shoot from a clean barrel (like hunting) then you need to duplicate the conditions, ie, a clean barrel, for each shot. Yes, it is not good for the barrel to clean it that often.

The sporter barrels may also change POI with changes in temperature. You should also check to make sure your barrel is not touching the stock after it has heated up from shooting.

You are smart to be starting with the .223 It is a *****cat to shoot. I'd recommend that your second rifle be the 6.5CM. The recoil difference between the .223 and .308 is pretty big (my BVSS is in .308). If you are shooting MOA size groups you are doing well. Many people cannot manage to do that on a consistent basis. Consistent 0.5MOA is the realm of competition shooters.

Last, if you plan on shooting a lot and don't reload, consider investing in a reloading setup. A single stage or something like a Lee turret press are really inexpensive compared to the cost of good quality ammo.

PS noticed your build pics on the other thread. Nice rifle.