I could be wrong, but I think the plastic grips were always the basic standard for European market 65's, with the wood sporter grips and palmshelf match grips as optional upgrades there. Many bought the 65 as a high-quality sporter, not just for paper punching, especially after It was replaced as FWB's top match model by the models 80 and 90 springers, and later SSP and CO2 pistols.
The vast majority of 65's you see here in the US are Beeman imports, and just about all of those were brought in with wood grips. Beeman's sold plenty of other sporter pistols so I suppose the logic was to position the 65 as their top-of-the-line match pistol. They continued to push it with the top-of-the-line palmshelf grips, etc., even after its day in top-level competition had really passed.
