Just went to a burn rate chart, and AA 4350 was listed at number 136, from fastest to slowest, and IMR was number 137. I would think that they are pretty close, but, with that being said, with access to the internet, I would go to the company's website,AA and IMR's website, and see what they have published. DON'T go to joe blows website, but the company's involved. gypsyman