Let me try five possible linked reasons:
Fashion:
- Back in the late 70s and early-mid 80s, when tuning took off, everyone went break-barrel crazy. Apart from a few die-hards with Airsporters, MkIIIs, or Diana 50s.
- We also all went German crazy. All the best guns were German. Deffo.
- They were tainted by the military Jackals and not seen as truly serious guns.
Technical:
- The tuners recognised the limitations of the tap loader. I can’t recall anyone offering a tuned Tracker, for example. Early Venom made at least one tuned Airsporter, but did they sell any more? I doubt it.
Economics:
- They were already expensive without the cost of tuning. Even the base models were a little more expensive than an HW80, and about 20% more than an HW35 or Diana 45. The nice ones (Camargue, Khamsin) were a lot more (50%?).