Here you can get the stats for a profile, with this API call
https://my.callofduty.com/api/papi-client/stats/cod/v1/title/{{title}}/platform/{{platform}}/gamer/{{username}}/profile/type/{{gameMode}}
The previous API call was called V2, it is not available since few months before VG's release
https://my.callofduty.com/api/papi-client/crm/cod/v2/title/{{title}}/platform/{{platform}}/gamer/{{username}}/profile/type/{{gameMode}}/
The V1 can't access weapon stats, only category stats. So we can't get weapon information anymore.
You have a lot of information available so I won't explain a lot more.