375, I would expect you would need to anneal and resize only if the hulls became difficult to extract from the chambers. Are you buying wads or making your own? You might consider a larger diameter for your wads if there really is a sealing problem.
Note that it is repeated resizing without annealing that leads to cracks. A fireformed hull should be able to withstand a large number of loadings if it is shot in a matchin g chamber and not resized. Annealing brass "softens" it and reduces "spring." A freshly annealed hull will "spring back" a few thousandths of an inch (sufficient for easy extraction from the chamber) after first firing. If the hull is repeatedly fired in a larger chamber and/or repeatedly resized, it will work harden. If the hull is hard enough, it will spring back too much and continue to get harder until it cracks. The trick is to match hulls to a chamber while they are still relatively soft and keep them with said chamber.
DDA.
