AMR isn't lying to you. It's showing you what it is told to. A tool is only as good as it's user
Their base stat values aren't bad and they should still be quite accurate for you gear but once you get some better gear, the difference will grow and you're better off using your own custom values which you can gain via simcraft (I'd just suggest running at least 10k iterations. 1k is still so low that rng can skew the results in a noticeable way.).
If you still have questions regarding simcraft in combination with AMR, I'd suggest you read This guide about the topic