Oh dear oh dear.... First off people on cypherpunks seem to have the idea that the type of people who go blasting peoples heads off have brains. Without wanting to inflate people's egos too much the average reader of cypherpunks is an awful lot smarter than your average criminal. Fancy plans to disolve gun barrels etc are way too complex for your average criminal and in any case it is substantially easier to drop a gun in a lake or the sea and less likely to result in incrimination than to try disolving it, run 200 rounds through it or whatever. Vacuming up powder left over from a rifle range would not help very much. One of the problems of building a bomb is to make sure that all the explosive goes off. A gas chromatograph is able to differentiate spent and unspent explosive. It would be easier to go off and buy the stuff from multiple sources or to make ones own explosive from nitrates with oxidants. I would expect that anyone vacuming up the residue from a gun club is likely to have difficulty explaining what he is doing. After all one does not usually go off to play Rambo, then stick an apron on and start doing the housework. I personally think that tagants is an insuffieicent approach to the problem. Given the number of gun related homicides in the US it is not unreasonable to require each individual cartridge to be stamped with a serial number and for gun dealers to be required to record each individual purchase. That at least was my advice to the UK govt after Dunblane. If people go arround claiming that ownership of guns is necessary so that people can commit acts of treason against the US govt then it is inevitable that there will be pressure for greater regulation. The NRA has been playing a bad hand stupidly. By raising the militia argument they have played into the hands of abolitionists. It would be entirely foolish for the crypto lobby to allow themselves to be tied to the NRA. The NRA has no choice but to support civil liberties, there is no reason why the wider civil liberties movement needs to support the NRA. More significant for crypto policy is the recent revelations about US spying on the European Union by spoofing CISCO routers via SNMP. That act should be exploited to drive a wedge between US attempts to bar use of cryptographic security systems and the members of the EU. Phill