Files that contain the .bc! File extension are most commonly associated with the BitComet P2P file-sharing application. This BitTorrent-compatible app uses the .bc! extension when it begins a download that is not completed.
If the BitComet app begins downloading a file and the download is interrupted, the software will save the partially-downloaded file with the .bc! extension. When the download resumes, the software will rename the file with the appropriate fill extension once the download has been completed.
It is important to note that if a download is interrupted and is no longer on the BitTorrent server once it can resume the download process, the file will just remain on the user's system with the .bc! file suffix.
Try a universal file viewer
File.org aims to be the go-to resource for file type- and related software information. We spend countless hours researching various file formats and software that can open, convert, create or otherwise work with those files.
If you have additional information about the BC! file format or software that uses files with the BC! suffix, please do get in touch - we would love hearing from you.