steve004 said
I don't know why as I'm not much of a S&W guy - but my immediate reaction was Model 39.
https://www.gunbroker.com/item/1152602106
  

you know - you are very likely correct! 

https://www.gunbroker.com/item/1152602106

Deg said
Is it safe to ask a S&W question?
  

Yes, go for it!

What chambering?

Mike

There is no known “official” statement from Winchester (or its later corporate owners) explaining the reuse. Extensive searches of Winchester histories, factory records summaries, collector publications, and the company’s own timeline/FAQ turn up nothing—no memos, catalogs, or executive comments addressing it. 

The best (and only substantive) explanation comes from knowledgeable Winchester collectors and historians, particularly those associated with the Winchester Arms Collectors Association (WACA). In a dedicated discussion on this forum, WACA Historian Bert H. addressed the Model 59 pair directly and offered the same logic that applies to the Model 55s:

“I suspect that somebody at Winchester forgot about the Model 59 .22 rim fire rifle. It was developed in 1929, and only marketed for one year (1930). It was discontinued after just 9,293 were manufactured. The Model 59 Semi-auto shotgun arrived on the scene 20-years later in 1959, which leads me to believe that whomever it was that assigned the model designation to it, was unaware of the Model 59 rifle from 20-years earlier. Of course, this is just my guess.” 

The same reasoning fits the Model 55s perfectly: the lever-action version was discontinued in the early 1930s, and the .22 version appeared ~25–30 years later. Both early models were relatively low-volume or short-lived (especially the Depression-era .22s), so by the late 1950s/early 1960s—when Winchester was rapidly introducing new budget .22s and shotguns under new corporate ownership (Olin)—the prior uses of those numbers had faded from institutional memory.

Why not just pick a new number? Model numbers at Winchester were primarily internal marketing/designation tools rather than strictly controlled, trademarked, or sequentially “reserved” identifiers. There was no production overlap, no parts interchangeability issues at the time, and no consumer confusion in the marketplace because the guns were sold decades apart in completely different categories (centerfire rifle vs. rimfire plinker; rimfire rifle vs. shotgun). Winchester was churning out new models rapidly in the post-WWII era, and a simple two-digit numbering system made reuse administratively convenient. The company almost certainly never imagined that collectors decades later would be cross-referencing old catalogs and serial lists.

In short, it was an unintentional oversight driven by time gaps, low production of the originals, and a lack of any formal “model number registry.” It has created minor confusion for modern collectors and appraisers (you always have to specify “lever 55” or “.22 55,” for example), but it wasn’t a problem for Winchester at the time. No evidence suggests it was done deliberately for any strategic or marketing reason.

Why did they do this?  Winchester must have been aware that this would lead to some level of confusion for all involved, so why not create a new model number?

Has there ever been any sort of 'official' statement from Winchester as to why they chose to duplicate a model number?  

What is the best explanation for why this was done?

Paul