I am planning on swapping from IMR 7828 SSC to Retumbo in my 300 weatherby. This is an effort to reduce the number of powders I've got to keep around and I figure that Retumbo should work well with both the 338 lapua I'm having built and my 300 weatherby. But my concern is that Retumbo will burn to slow for my 300 that wears a 26 in barrel and pushes a 200 grain accubond. But on the flip side I'm thinking that I shouldn't have any issues with Retumbo in a 338 lapua with 28 in barrel and pushing a 300 grain bullet. Any thoughts?