With the limited pellet choice that doesn't surprise me and I have read posts where the Hw100 was said to have had a less than favourable .20 barrel fitted.
As Weihrauch still sell special order .20 rifles, I would have thought it shouldn't be to much to ask, for H&N to do limited runs of their old .20 pellet range, I believe that request would need to come from the likes of Hw to make it happen though.
Imagine if Weihrauch suddenly out of the blue offering limited runs across the board of their rifles all in .20 but with the added lure of high grade walnut stocks with hand cut checkering in the style of yesteryear, be that their own of their own designs or in homage of Venom V Mach, who really put Hw at the top for much sort after custom tuned spring rifles.
.20 may have been pushed in the corner but every corner has a turning