The thicker shaft stoppers may indicate that Richardsons learned how fragile the thin ones were - and yet the thick ones are still broken off!
Regarding the age of your bottle, that is a difficult question. I think the ones from around 1900 - 1910 tend to have a foot rim, and often have an outer ring of white quatrefoil canes, and an overall lighter colouration. I have had a few darker weights, often not quite as well finished, and I suspect they are from an earlier period. I feel your bottle is an earlier piece, too. The problem is that might be anywhere from the 1850s to 1890s, and I do not know of any evidence to tie these pieces in to a specific date.