I suggest you post your problem in the Gunsmith forum and get some advice from possibly a qualified gunsmith rather than asking those who may not be qualified to answer such a question.
Obvously, you've got a major and very DANGEROUS problem, but as a Model 99 owner/shooter/reloader, I've never heard of this problem with Model 99s.
I also attend a forum on another site that specializes in Model 99s... and I've never seen such a problem posted there either. And so, I'd guess this isn't a "normal" problem with Model 99s.
I sincerely hope you find the answerand can repair your rifle since your distance from a gunsmith makes taking it to one very difficult.
Strength & Honor...
Ron T.