The good news is that December 2025 still has a couple of working ones, and they give you a nice chunk of seeds right away.
These units consistently dominate high-level play across expert rankings.
CoD MW4 Weapons Max Leveling from U4GM is designed for players who want to take a selected weapon to its maximum level without completing the entire leveling process themselves. The product page lists options for individual weapons across multiple classes, with the service focused on maximum weapon progression and the corresponding Apex Attachment unlock.