First, a description of what a “bullpup” rifle is: The firing chamber/action/magazine is located behind the trigger instead of in front of it. There have been numerous bullpup designs, and they came into a fad in the 1980s. Of course, this brought up the biggest issue with them.

Basically, it’s easy to make a bullpup simply by flipping around a conventional rifle. However, that doesn’t make for a good bullpup the way a ground-up design does. However again, rifles are such a small part of (especially high-intensity) war that the decision to make a big investment in them is not made lightly. However however again, the impetus for bullpups was basically “they need to be short so they can fit in vehicles more easily”, with performance being less of a concern.

Of course, shorter-barreled conventional rifles took most of the wind out of the bullpup’s sails. But they continue to be used. They just haven’t dominated.