This is copied from a post of mine over on the 1911 Forum:
1991 vs. 1911
In case you are wondering what the differences are between these pistols..... there really aren't any significant ones. The M1991A1 (or simply "1991") is just another version of Colt's 1911-type pistol, and as its name implies was introduced to the market late in 1991. The name "M1991A1" was little more than some Colt marketing exec's clever spin on the original US military M1911A1 designation. It was a basic Series 80 pistol with less frills than a standard blued Colt Government Model which enabled it to sell at a lower price point, and thus better compete with the Springfield Armory and Norinco pistols that at the time were starting to chip away significantly at Colt's market share. The 1991's no-nonsense military appearance was actually promoted in Colt's advertisements for the pistol, and in fact the serial number range purposely picked up where the original US military contract pistols left off in 1945. This was in spite of the fact that the new pistol was a modern Series 80 version of the 1911, and not a truly accurate reproduction of the original government-issue pistols. "No frills" features included the matte Parkerized finish (later changed to matte blue after a couple of years), black plastic checkered grips (which had a tendency to crack and were soon replaced with similar ones made of rubber), a nylon mainspring housing (flat serrated type) and nylon trigger pad (long smooth-faced style), plain black high-profile sights and a simple "COLT M1991A1" slide rollmark. Aside from these changes they were made to the same quality standards as all other Series 80 Colt pistols of the same era, although a year after the M1991A1 was introduced the rest of Colt's 1911 line received some pretty radical external changes in the form of their so-called "Enhanced" line of pistols. Around 1995 or so a stainless version of the M1991A1 was also introduced.
Technically the 1991 is still in production, although in late 2000 it was upgraded with a semi-polished surface on the flats, stainless barrel, aluminum trigger pad and checkered wood grips (stainless models retained the checkered rubber), and is no longer officially called the "M1991A1". It's now simply a Series 80 Government Model, and as such the newer slide rollmarks reflect this change. Because of this Colt enthusiasts now refer to the older pistols as "Old Rollmark" (ORM) guns and the newer ones "New Rollmark" (NRM). The SKU's are still the same however, #O1991 for the blued model and #O1091 for the stainless. The earlier guns are easily identified by having "COLT M1991A1" in large block letters across the left face of the slide. The NRM Colts will have three smaller lines of text saying "COLT'S-GOVERNMENT MODEL-.45 AUTOMATIC CALIBER", along with Colt's rampant horse logo.
The Series 70 reproductions differ from the current 1991 line in that they are better finished (finer degree of polish on the flats), have steel triggers and mainspring housings, and lack the firing pin safety. Because of the modest upgrades they are priced slightly higher, but the overall quality of either the 1991 or Series 70 models are about the same. Differences are primarily cosmetic.
Enhanced, XS, XSE Models
In 1992 Colt modified almost their entire catalog of 1911 pistols to include features that they felt would "update" their product line in the face of the increasingly popular factory-custom 1911 market. The changes were:
*Flat-topped slide with a plain rib and angled Gold Cup-styled cocking serrations
*Narrow-hood Gold Cup-style barrel
*Undercut front strap below the triggerguard
*Oval-cut round hammer and flat "duckbill" style grip safety
*3-dot high-profile sights
*Beveled magazine well
*Lowered and flared ejection port
*Long nylon trigger and flat nylon mainspring housing
*Pebbled rubber wraparound grips
All Government, Commander, and Officers ACP pistols underwent the change except the budget-priced M1991A1, which remained Colt's sole "classic" offering for many years. While some customers liked the new changes, others didn't. Those opposed fell into two camps: the 1911 purists (including yours truly) who opposed such radical changes to such a timeless and classic design, and those who felt that the "upgrades" Colt made still left much to be desired in the face of what other companies were offering. Sales of the new Colts remained lackluster until Kimber came out with their own 1911 in 1996, after which sales of Enhanced pistols dropped like a rock. Colt's response was to quietly replace the Enhanced line in 1998 with the new XS series, which added a proper beavertail grip safety, proprietary wedge-style rear sight (by CMore corp.), extended thumb safety and a return to the round-topped slide (but still with the Gold Cup-style barrel and angled slide serrations). For whatever reason Colt had trouble maintaining the product line (due to credit issues with the parts vendor, see below), so in 1999 (just a year later) the XS series were replaced with the XSE line, which dropped the beavertail and wedge sight and replaced them with the standard Colt "duckbill" safety and plain-jane 3-dot rear sight.
Today the XSE series remains in production, but with numerous upgrades that finally makes them a truly excellent product that compares favorably to other manufacturers' offerings. Novak-style front and rear sights, a true S&A style beavertail safety, alloy 3-hole trigger, and checkered wood grips are now standard. But as you can see it took awhile for Colt to finally get there, and now that their pistols are among the best on the market demand is high and they can often be hard to find.
I have to admit to being out of the loop on this, unfamiliar with the term "self-lubricating plastic" and its characteristics. So I did a very brief search. Just a brief quote here: "Self-lubricating plastics help improve efficiency with decreased maintenance, impact absorption properties and an extremely low coefficient of friction which increases speed and reduces wear. Benefits: Exceptional resistance to wear and abrasion High Impact strength…" Guess I learn something new from this forum every day.The Colt factory plastic mainspring housing gives no problems.
I think in the years Colt has used it on some models, I've heard of about one person who had a housing split.
In fact, some Match shooters installed polymer housings to get a slightly better trigger pull due to the self-lubricating plastic.
Plastic housings used by other makers do have some history of failures, usually splitting open, but not Colt who either used a better plastic or simply made sure they were better made.
Nylon triggers give no problems.