A few days ago, I asked around if there was a free metal drum groove library. The answer seemed to be no, so I've put together a quick website to freely share metal drum grooves to the community.
If you'd like to contribute, there is a page to upload, with you listed as the author. I'll move them to the correct categories. I am still uploading my own grooves. Feedback is welcome.
https://sites.google.com/view/metal-midi/