For a more complete picture I offer the following:
Case prep. For most of my primed brass, they were sitting primed since about 1980. That suggests sized, trimmed and de-burred at the neck (in and out) as that I did back then. They were not cleaned. Now to the present - they were wiped outside, then after successfully loading about 75 and experiencing the case collapse and the first of your replies I brushed out the necks and neck sized and loaded until I ran out of IMR-4198 (bought pre-1980).
With my dial caliper I had checked case length and loaded length. LOA was to butlersrangers suggested 2.760. This dimension continued to be checked every few rounds due to concern over the few that showed slight bulging at the shoulder. I also, following parashooterss comment, checked the seating die for crimp as he suggested. There seemed to be resistance with and empty case and the die was backed out a bit, one case loaded and LOA checked. I set the seater down a little to achieve 2.760. Once convinced the rounds were within spec I loaded our the last of the 4198.
Future loading once past the lot of primed cases will include clean if not new, necksize, trim, chamfer, prime, load. With 500 more 110Gr. and several hundred more up to 180Gr RN, I will need more brass soon.
Thanks again to each of you for your input. My old shooter thanks you -
