FJ is perfectly fine as is. It reduces explosive damage. However, once that first explosive hits the user has very little health left and practically anything else will finish him off. If the FJ user already has taken damage, a single explosive will take the user out. What would be the point of even having a perk that reduces explosive damage if explosives still killed you in one hit without any prior damage seeing as all of the lethals have virtually the same damage and blast radius? If you are having issues killing FJ users then you need to rethink your explosive strategy. Start considering your explosives as a means to soften up your opponent instead of a guaranteed kill and when you do get kills from your explosives you will appreciate them more.
I think ur calculations of requiring 2x is incorrect...actually its overkill if u do so...once a FJ player gets hit by an explosive (that would kill a non FJ player) player health is so low that even a flash can kill him...so stop complaining and put 1 bullet into him...! If FJ doesn’t stop explosives what’s the point?
And crossbow...i have close to 1k kills with it (i know its now much) never had an instance where i stuck someone and it gave me the flack jacket sign...maybe I’ve been really lucky not to stick a FJ user in that 1k kills...but highly doubt that the case.