Hi Filiberto,
I remember those threads. For my own part, I try to avoid the quicksand of whether a Hegira rug date is expressed in the solar or lunar calendar, mostly because my rugs get older when I use the lunar version.
Anyway, see additional comments below.
Regarding the weaver lopping off the initial "1," I don't doubt that it happened. I always wonder
why it happened. Was there a conventional usage by which people in those societies expressed a date ignoring a millenium? Maybe!
As to a rule of thumb, mine is that I keep in mind a Hegira date in 1300 using the lunar calendar lands in about 1882 by the western calendar. That is a handy reference date for most dates on rugs, at least the ones the likes of me and probably most Turkotekkers get to handle. It is easy to add to or subtract from that date. I assume, as you suggest, that Chuck's conclusion of mid-nineteenth century is based on a solar calendar. Using a lunar calendar for 1233 would put the rug before 1820.
Rich