I saw this one coming..

[sniper7]

we need to do background checks on cars, rental trucks, ammonia, fertilizer, any type of container or canister or pipe that could be used to construct bombs. moreover, we also need to have a door to door search and have anyone that has these items in or near their place of residence arrested and interrogated.

and just because that PVC pipe is used for your plumbing...doesn't mean you aren't planning on building bombs with it....

[Uberjager]

Even if you accepted the "hurr durr the 2nd amendment only covers muzzle loaders" argument, this would be an extreme violation of that.