...of restrictions on guns, reloading materials, and any sort of identifiable chemicals. (Because chemicals!)
The Al-Quaedish instructions for making crude bombs? Call for using match heads and sugar. Not commercial gunpowder, whether black or smokeless. 'Cause, you know, in most places where these guys operate you can't just walk into the neighborhood sporting-goods store and buy a can of powder for your smokepole.
I'm reminded that the last round of restrictions on the sale of blackpowder, back in the 60s or some such, was driven by a Dick Tracy story line. ZOMG a bad guy in t3h funny papers is using blackpowder in a highly-contrived arson scheme! We gots to ban itz!
And, should matches not be available? Why, the good folks at the Frankford Arsenal addressed that one long ago (and in more practical fashion than the Rocket City Rednecks). Look up TM 31-210. Got salt, water, electricity, sugar, and time on your hands?
Update: and if we're looking at deflagrating compositions, I stumbled across a doozy back in high school*. Two ingredients**; one easily found, while the other took a bit of looking for. Part 'A' remains as easy as ever. Part 'B'... well... I haven't looked for it in stores in a great long time now, but it's probably there if you look in the right places, and I just discovered that it's unexpectedly easily bought on line***. Maybe even without getting on any (more) watch lists.
* I was trying to make pretty colored fire. What I got was quite an impressive bang, from a small amount of the mixture with very light confinement. Thanks to the very light confinement, the fragments thrown around by the blast were bits of paper, and didn't go too far.
** Two ingredients, considered at the retail level. At least one of them has several different chemicals in it.
*** Oh, and it can also be made at home, without too much effort, from materials which are and will surely remain ubiquitous.