Gyrojets never took off because of how expensive they are to produce compared to conventional ammo. ($10 vs $0.50) Their only advantages are gun size and recoil.
Micro drone guns might actually be the one use case for gyrojets, because recoil and barrel weight are the most serious issues.
I thought the major issue was that they were extremely vulnerable to being blown off course during the slow-moving launch phase. Basically, that even a mild crosswind would send it irretrievably askew.
I assumed that the price issue could in theory be solved by mass production economies of scale, if the other issues could be sorted out.
Micro drone guns might actually be the one use case for gyrojets, because recoil and barrel weight are the most serious issues.