I have good luck with slp 2000 looks like pink antifreeze, was designed for cleaning m16 bolt carriers to remove carbon. Best part it is water soluble.
You are partially correct, beneficiary doesn't need to be specifically named. Who ever is the person handling the estate can sign off on the form 5, if the new owner is family or friend . I have dealt with this on 4 different occasions in the last 10 years . Surprisingly the ATF expedites these...