How could gunpowder be inventable/refinable, but not percussion cap primers, with the least collateral damage to the world?

Question

While gunpowder has been rightly characterized as one of the greatest leaps forward in the lethality of weapons, guns required some companion inventions to become the dominant small arms weapon system of the current age. Since I'd rather not have guns be the dominant weapon system in the world I'm building, I'm looking to block at least some of these ancillary inventions so that guns remain messy, relatively unreliable, and decision-demanding, leaving room open still for closing to melee combat as a practical matter of course.

In particular, one of the companion inventions I consider key is the percussion cap: a small metal piece that holds a small quantity of primary explosive, or primer, that explodes when the cap is struck, initiating a propellant charge or other firing train. While stopping people from shaping metal into a certain form is certainly not a practical way to worldbuild, making it so priming explosives are a chemical impossibility seems to be like a decent approach to this problem. Furthermore, blocking the percussion cap from being invented has the desired effect -- without percussion caps, you can't have weatherproof, high-reliability cartridges, nor can you have easily operated breechloading firearms (never mind not being able to develop autoloaders).

Therefore, I ask one question: what changes can I make to my world so that priming explosives are not discovered/invented while causing the least amount of collateral damage to other parts of the world? (In particular, biochemistry in the world still needs to be Earth-like, as far as is possible.)

Answer 1

Percussion caps can be delayed but can’t realistically be prevented without serious rearrangement of history or the use of magic. The longer the time period of the delay the harder it will become to prevent the invention and the greater the distortion of reality.

The problems being the shear multiplicity of chemical compounds, other technological solutions and human ingenuity. If one compound used in percussion caps is prevented (perhaps by making Mercury very very rare so no Mercury fulminate) Silver fulminate would be discovered and used a little later. If fulminates are hand waved away somehow percussion caps could still be made with lead or Silver azides and if those were excluded there are many more Lead styphnate for instance.

Ultimately in the modern age a range of different technologies could be adapted for use as detonators involving pressurised gases, electrical ignition or the mixing of hypergolic (spontaneously flammable) materials in confined space

Answer 2

Trying to prevent a technology from being created is very difficult. In general it's best to just handwave it and leave it at that.

If you need to actually stop a technology from taking root, I find the easiest way to do it is to turn to the most powerful handwavium you can get: religion. If the world's major religions all have clauses which make explosives frowned upon, its effect will delay primers substantially.

For an excellent example of this working in a science fiction world, take a look at Frank Herbert's Dune. Frank wanted a world that wasn't dominated by computers, so he staged a great war against the "thinking machines," known as the Butlerian Jihad. One of the outcomes from this was that every civilized planet in the galaxy was seeded with the commandment: "Thou shalt not make a machine in the likeness of a human mind." Herbert's world is rich with all of the solutions people came up with to get around this limitation, like the Mentats, but actual computers never showed up in his work.