Try the Speer 400. I use the two brands interchangeably in my Marlin, went to the Remington because they were a lot cheaper and all I shoot is paper with my 45/70 anyway. I use the same load of IMR3031 with either bullet and they are equally accurate (scary accurate) out of my M1895 levergun.
You say you usethe same load for both, Do they shoot to the same point of aim?
thanks tom
BTW the in stock date at Midway on the rem 405's is now May 7.2012