Late to the party here but no matter what I do I can't get the ammunition for TMP (+variants), PP-2000 (+variants), PP-2000 "pocket" or HK53 to spawn. You should know that I use RH_HK416, RH_M4, RH_M14, RH_MGS, RH_MK18, RH_PDW, RH_Pistol and RH_SMG and along with ACE2+ACEX, AAW, AEK and UKweps and got all three DLC's. I have over thousand of items and successfully spawned and tried them all in game. Except for one launcher these four are the only items I can't make work. Interestingly, all the MP5's work and use the 30Rnd_9x19_MP5 ammo!
According to the readme the right ammo should be;
RH_HK53 = 30Rnd_556x45_Stanag
RH_pp2000 = 30Rnd_9x19_MP5
RH_pp2000p = 30Rnd_9x19_MP5p
RH_tmp = 30Rnd_9x19_MP5 or 30Rnd_9x19_MP5SD
I run the game with ACE and use Robalo's update. As far as I discovered, it replaces 30Rnd_9x19_MP5p with 30Rnd_9x19_MP5. This shouldn't really matter though.
I have also tried this with Ghost's V2 script that should add every accessible item into a crate, this also fails to add the ammunition for these items.