A question about certs

[SexyTRex]

I am having a problem with my certs and wasn't sure where to take my query. I amassed some points and drop into a red dot for my rifle and claymores but when I go to equip them they don't show up not sure if I'm missing something or if it's a bug.

Also bursters and flamethrowers don't show up in my certs screen, do I need to be a certain battle rank to cert for them?

Any help would be lovely.