Firearms are fairly well defined. Hacking tools are not, and most likely will not be well defined by the legislation. Is ping a hacking tool? Wireshark? tcpdump? a hex editor? telnet? all are used in hacking, but also have legitimate uses.
You might be interested to know that trivial metalworking can construct a piece of metal (known as a sear) that becomes legally classified as not just any firearm, but a heavily regulated machinegun -- because when placed in the corresponding firearm, replacing its original sear, it can make the firearm capable of full-auto fire.
The ATF also considers soda bottles to be suppressors, aka silencers, if there are any suspicious circumstances. Same for any metal tube that's threaded or otherwise easily attached to a firearm barrel. ("Silencer" is a misnomer; they are not silent; they generally reduce noise by roughly 20-30 dB.) Even possession of (1) a gun, (2) a soda bottle, and (3) duct tape, in close proximity, would motivate the ATF to charge you with a firearms crime. Unlike many european countries where such devices are sold without a license and it's considered rude to hunt without one, in the U.S., hysteria over organized and gang crime caused many things to be irrationally banned or strictly regulated, including suppressors and switchblades. [2]
There's also the "rifle" vs "short barreled rifle" classification. The term AR15 is a category of firearms that can range from stockless (nothing to rest against the shoulder) and very short barreled (circa 5-8"), to long range variants that have shoulder stocks and barrels 22" or more. If you buy a rifle variant of an AR15 and buy a short barrel, you've committed a crime. The receiver (the central metal piece that accepts the ammo magazine), because it was originally part of a rifle, is forever classified as a rifle receiver. By converting it into a handgun-like firearm, legally speaking you have converted it into a SBR, or short-barreled rifle, which requires beaucoup paperwork in order to be legal.
In contrast, if you start with a handgun-classified variant of the AR15 [1], no special paperwork is required.
tl;dr : there are some absurd classifications of objects as firearms, or firearms as more heavily regulated types of firearms, that a reasonable person would not understand or comprehend.
Regardless of the merits of firearms classifications, those distinctions are documented, and firearm design doesn't change nearly as quickly as computer technology. It seems unlikely that there can be a reasonable classification of "hacking tools" that would ever make the criminalization of mere possession make sense.
