I ordered a Redding Full Length Type S bushing sizing die for my 300 Win Mag. To select the proper sizing button they suggest getting one that is 0.001" smaller than the loaded round neck diameter. I am using Lapua cases and they are measuring 0.3355 to 0.3363". So I got the 0.334" titanium bushing.
But in checking my loaded round neck diameter I decided to measure some bullet diameters and found that the box of Nosler 200 Accubond bullets that I have on hand were 0.3075", not the 0.3080" that I expected. Does this matter much or would they still obturate adequately to avoid any gas blowby? Would them being undersized cause any accuracy problems? Thanks, Rufous.
That is the key and way Redding talks to do it (.001 under the smallest avg neck diameter of the loaded rounds). Also if you read carefully they are intimating neck turned cases which is normally BR standards, ie single shot and very little neck tension.
they also state that using Type S bushings and unturned necks, go .002 under the smallest average loaded round.
It looks like you gave the unloaded case neck dimensions. That is not an accurate way to determine what size bushing.
Also you may find that only .001 neck tension is not enough to hold the bullet in the case with the recoil of a magnum in a magazine. Testing shooting with loaded mag will tell you if they creep forward.
Rufous, my thinking is I can't imagine going to all the trouble of using a bushing style die meant for precision reloading as Bounty Hunter pointed out and then crimp the neck. why mess with all that fine tuning technique if you're gonna crimp?