Tight necks are a P.I.T.A., with little to no benefit apparent until you spend a huge amount of time and effort to get to benchrest (or near-BR) levels of precision.
I would seriously suggest that you consider having a gunsmith run a non-tight-necked reamer into your chamber. That way you wouldn't have to turn your necks. A .308 Obermayer, or a '95 Warner Palma, would be good choices.
Standard fullbore competition rifles have "min spec" necks, i.e. they'll chamber factory ammo but they are at the small end of the tolerances. For example, my .308 Obermayer chamber gives fired brass with .343" neck diameter, so it's probably a .344" neck. This will safely chamber all factory ammo, which is a nice plus. With thicker necked high quality brass (Lapua), the loaded rounds are about .337" o.d., which gives about .006" of neck expansion upon firing. With thinner necked brass (e.g. Norma, Winchester) the loaded rounds have a neck o.d. of .333"-.335".
Some fullbore shooters, American in particular, have tried to apply benchrest rifle and ammo practices to fullbore (e.g. fitted necks), with surprisingly little added performance.
Standard fullbore competition rifles will shoot 1/2" at 100 yards, and about 10" at 1000 yards. Unless you have reached these levels of performance, and wish to go further, don't feel hindered by having a "sloppy" non-fitted neck chamber.
Good day I have a 308 with a 334 neck diamater I was wondering if someone could walk me through the steps on tuning the neck for chamber tolerance?
