The Big Book of Gun Gack – On sorting brass for consistent neck thickness, for instance:
You may need to anneal case necks, even on new brass. Yet another difference between top-notch brass and common brass is consistent annealing. Not long ago my gunsmith friend Charlie Sisk called me on his smart phone, asking what could possibly be wrong with some 7mm Remington Magnum cases he’d purchased.
Charlie normally buys big batches of new brass, loads them once, then sells the fired brass, saving him time that’s more profitably used by actually making rifles, rather than resizing and trimming fired brass. But none of the 7mm Remington Magnum rifles he’d made shot worth a hoot with the new batch of brass, yet the necks were pretty darn uniform.
After we’d talked for a while, I came up with a SWAG (Scientific Wild-Assed Guess) and asked, “Have you tried annealing them?”
“I’ve never annealed any brass. Why would I?”
“Well, it might not have been annealed right at the factory, so bullet pull varies.”
After I described Fred Barker’s easy candle method of annealing, we hung up. (Well, we didn’t actually hang up, a term left over from land-line days.) A couple days later Charlie called again, saying he’d annealed a few cases and loaded them up. Loads that formerly shot 2-inch groups now went around ½ inch. So sorting brass for consistent neck thickness may not be enough.