 He then changed the 35-degree shoulder to 40-degrees and the .280 Ackley Improved was born.If barrel length and chamber pressure are equal, the .280 Ackley Improved is about 100 fps faster with all bullet weights than the standard .280 Remington.In 2007, ammunition manufacturer Nosler registered the .280 Ackley Improved with SAAMI and began providing factory loaded ammunition and rifles for it.