How to handle security after working with volatile material? [duplicate]

There are many legal reason to have worked with explosives (anyone could make his own ammunition at home), and TSA agents know that of course, so there is not much to worry about. Having your membership card with you is certainly a good idea, as it makes your claim convincing (but you are not required to have it).

Worst case they will look through your hand luggage in detail, to make sure there is no hidden bomb, so plan for an extra five to ten minutes.

Failing the explosives residue test is not something that will cause you to not be allow through security - it is simply a red flag that will cause the security staff to carry out additional checks.

Those checks will most likely involve them asking you if you have been around any explosives - at which point you can explain to them your club membership and activities. They will also probably involve them paying more attention to your carry-on (and possibly even checked) bags to make sure you are not transporting something you should not be - not just something with bad intent, but even just something that you might not realize is not allowed on the plane, such as one of the rockets.

At most, I would suggest allowing a little extra time to get through security just in case you are randomly selected - although even that likely wouldn't be needed.

Speaking from personal experience, one of my carry-on bags did trigger the explosives test once when I was randomly selected. I have no idea why it set it off, but after a few minutes of further tests and bag checks I was let pass through without any issue.