I'll take a stab:
From 1900 to the early 1960's the police shotgun market was shared by Winchester and Remington.
Winchester had the larger share, with a few makes like Ithaca, High Standard, and Stevens having at least a "toe hold" in the market.
In those days, pump shotguns were made of forged and milled steel, and as such, were pretty well 'bullet proof". Since the guns were so strong, they were all very reliable, and lasted for years in service.
Coupled with the fact that most departments didn't put guns in patrol cars, and the guns tended to see less use back then, the typical police shotgun lasted just about forever.
This meant that police choice came down to price and the people doing the selection's personal likes and dislikes.
The great "Sea Change" started in 1950 when Remington introduced the Model 870.
This was the first shotgun made with modern production methods. Although Remington used high-speed production methods, the gun still used a forged steel receiver, and robust fabricated parts.
So although the smaller parts weren't milled steel, they were sturdy and foolproof.
The problems started when the other gun makers realized that they could no longer continue to produce the old milled steel "tanks", and designed new guns made with stamped parts, and then, cast aluminum receivers.
The simple fact was, that although the designs looked good on the drawing board, and often stood up to civilian sporting use, they simply couldn't take the abusive use police put them to.
Exacerbated by the fact that police began to put shotguns into patrol cars as "standard equipment", the new stamped and fabricated guns failed to stand the use.
The worst example of a miscalculation was Winchester's loss of the police market they once dominated.
In 1964 Winchester made the notorious decision to change their entire line of firearms to allow cheaper production.
Prior to this, Winchester had a large share of the police market with their 1897 and 1912 Models. Because of the incredible durability and quality, it wasn't unusual to find departments that still used the '97, and the "average" police shotgun was a Model 12.
In 1964 Winchester introduced the new "Super gun" the Model 1200. Like the other new generation of post-war guns, it used stamped and fabricated parts, and an aluminum receiver.
The gun was a disaster in police use.
The gun simply failed to stand up to the treatment, and police departments made clear their dissatisfaction.
Winchester analyzed the failings of the 1200 and redesigned the gun, reissuing it as the Model 1300.
Unfortunately the 1300 also failed in service.
The problem wasn't a specific weakness that could be diagnosed and fixed, but was a systemic problem. The guns simply wasn't durable enough.
Police departments first complained, then "voted with their feet", by refusing to buy anymore Model 1300 guns.
Since that fiasco, no police agency of any size has bought the Winchester Model 1300, and only a few small departments anywhere have used it.
The decision to stick with the 1200/1300 design cost Winchester their majority share of the police market, and through that reputation, Winchester lost their commercial share also. Today Winchester is number three in shotgun production, well behind Mossberg, who is well behind Remington.
In the 1980's Mossberg began to surge in shotgun sales, and made a move on the police market.
Unfortunately their model 500 suffered the same fate as the ill fated Winchester 1200/1300. The Model 500 also failed to stand the treatment.
Mossberg succeeded where Winchester failed, by upgrading and beefing up the 500 into the more sturdy 590 versions.
By this time however, Remington had captured the lion's share of the police market with their remarkable Model 870.
The heavier internal parts, and the steel receiver did stand the abusive police treatment, and has built an unequaled reputation for always working, and durability.
Remington's reputation allowed them to capture an estimated 90% Plus of the police market, and this in turn, helped them to secure the larger part of the commercial sporting market.
The last numbers I saw, indicate that Remington made almost TWICE the number of shotguns that their nearest competitor, Mossberg, made.
Other companies suffer problem similar to Winchester.
S&W decided to branch out into other markets, including an attempt to capture most the police market.
With that in mind, S&W started up an ammunition and holster line, along with their handcuff and other equipment lines.
The first S&W pump gun was the disastrous Model 916, which did serious damage to the companies reputation.
Determining to do a better job next time, S&W imported a Japanese Howa-made gun known as the Model 1000.
Basically a "clone" of the 870, the 1000 did better in the market, and for a time was a "status symbol" among individual police officers who purchased it.
However, the 1000 also fell prey to the street cop durability monster, and failed to stand up.
Shortly thereafter, S&W dumped the ammo, holster, and shotgun lines, so they could "get back to our core business of pistols".
The Howa was passed on to Mossberg, who filed to aggressively market it, and the gun soon sank into oblivion.
Other gun companies also failed the police test. Among them were High Standard, who's innovative Model 10A and 10B bull pup guns failed due to high price and reliability problems.
Savage/Stevens guns failed to sell to the police, and Browning made no effort in the police market at all.
Only Ithaca retained any share at all with their Model 37, but quality control problems, and a lack of adaptability finished them.
By now, Remington's 870 has such a reputation and actual proven performance, it's unlikely any competitor will shake their dominance of the market, at least as long as police continue to use pump shotguns.
Remington's design team's genius has given the company a market share and dominance Glock and other gun companies can only marvel at.
Although there are the usual disputes as to shotgun brands among civilian owners, there is no doubt about who who makes the most durable and reliable gun. The fact that you have to look long and hard to find a law enforcement agency that DOESN'T use the 870, tells the tale.
The police did 'vote with their feet" and it wasn't because they liked the way the Remington salesmen smiled.
All this points up the keys to the firearms market:
1. Design a sturdy, reliable, no-nonsense, firearm.
2 Insure the production quality make good use of the design.
Most companies either came up with a substandard design, or failed to obtain and maintain quality production.
Those that did neither succeeded.
The results are there to be seen.
High Standard is a memory, Savage/Stevens is a never-was, and Ithaca
pretty well sank without a ripple.
S&W makes nice pistols.
Mossberg is selling a few guns to departments based on their cheaper pricing.
Remington skips to the bank.
