Yep, Moisture could have been the issue.
BUT: I was using acetone! - but due to its age (bottle opened 6 months ago) - it might have already catched some moisture, that's why it reacted with the MgAl (mesh was 230)?
Regarding the CU Benzo, I agree that this salt is - IMO - quite safe with AP, because nearly insoluble.
A nother problem could have been, that my Cubenzo is "polluted" with Na2 SO4 (because I produce it from Na Benzo + CuSO4 -> Cu Benzo + Na2 SO4...). Na2 SO4 is soluble, but does it reacts with AP? that's the question...
NeighbourJ, thank you for the information on milling AP!! I ignored it, though the only ammonium compound that could decompose volently by itself was AN... Good that I just milled my AP maybe 4 hours...
Short story: I replaced the MgAl with Hexamine, and this was probably the good choice:
- burnrate is high
- flame is getting a better blue, lower temperature with the Hexamine
- no reaction, no warming of the mix, looks quite stable after 4-5 days drying.
Will test it as go getter tonight, and see if that work.