Colt 1911 Differences (A Basic Overview)

Thanks to Dan S_____ who posted this. It is info many will need...

Series 70 vs. Series 80


There have been a lot of questions posted by new members and 1911 owners as to what the difference is between Series 70 and Series 80 Colts. This question is best answered by giving the following history:

Colt is the original manufacturer of 1911 pattern pistols, having made versions for both the military as well as commercial market since regular production began in January 1912. The commercial versions were nearly identical to the military ones, differing only in markings and finish. Following World War Two military production ended, but the commercial guns remained in production with only minor changes such as deletion of the lanyard loop and a larger thumb safety shelf. These pistols are known to collectors as "pre-Series 70" guns, as they pre-dated the Series 70 guns introduced in 1971. It was during this year that Colt introduced the first major design change to the Government Model in nearly 50 years. In an attempt to improve the accuracy of production guns the barrel bushing was redesigned, along with the barrel. In this system the bushing utilized four spring-steel "fingers" that gripped the enlarged diameter of the muzzle end of the barrel as the gun returned to battery. By tightening the fit of barrel and bushing in this manner Colt was able to improve the accuracy of the average production gun, without going through the expense of hand fitting the older solid barrel bushing to the barrel and slide. Models using the new barrel/bushing setup were the Government Model and Gold Cup, which were designated the "Mark IV Series 70" or simply Series 70 pistols. It should be noted that the shorter 4 1/4" barreled Commander pistols retained the use of the older solid bushing design and thus were never designated Series 70 pistols, although one hears the term erroneously applied to Commanders from time to time.

The new "collet" bushing (as it came to be known) worked quite well, however it was prone to breakage if the inside diameter of the slide was too small as it caused the fingers to buckle, then later break from the stress of being wedged between the barrel and slide. On pistols with oversized slides the bushing didn't grip well enough, and accuracy suffered. Because of this the collet bushing was eventually phased out sometime around 1988, with the older solid barrel bushing design being reinstated for use in production guns.

The single biggest change to the 1911 design came about in 1983, when Colt introduced the "MK IV Series 80" pistols. These guns incorporated a new firing pin block safety system, where a series of internal levers and a plunger positively blocked the firing pin from moving until the trigger was pressed, thus eliminating the possibility of the gun discharging if dropped onto a hard surface or struck hard. In this instance however, ALL of Colt's 1911-pattern pistols incorporated the new design change so even the Commander and Officer's ACP pistols became known as Series 80 guns. With the previous paragraph in mind, it is important to know that from 1983 until 1988 the early Government Model and Gold Cup Series 80 pistols used the Series 70-type barrel and bushing as well, although they were known only as Series 80 guns.

There was one other design change made to the Series 80 guns as well, and that was a re-designed half-cock notch. On all models the notch was changed to a flat shelf instead of a hook, and it is located where half-cock is engaged just as the hammer begins to be pulled back. This way the half-cock notch will still perform its job of arresting the hammer fall should your thumb slip while manually cocking the pistol, yet there is no longer a hook to possibly break and allow the hammer to fall anyway. With the notch now located near the at-rest position, you can pull the trigger on a Series 80 while at half-cock and the hammer WILL fall. However, since it was already near the at-rest position the hammer movement isn't sufficient to impact the firing pin with any amount of force.

Regarding the "clone" guns (1911-pattern pistols made by manufacturers other than Colt), only Para Ordnance (SIG, Auto Ordnance, Taurus have since adopted it also) adopted Colt's Series 80 firing pin block system as well. Kimber's Series II pistols and the new S&W 1911s have a FP safety also, but it is a different system than Colt's and is disabled by depressing the grip safety. No manufacturers aside from Colt ever adopted the Series 70 barrel/bushing arrangement, so technically there are no "Series 70" clone guns. What this means is that design-wise most of them share commonality with the pre-Series 70 guns, using neither the firing pin block NOR the collet bushing. Because of this it is important to remember that only Colt Series 80 models, and a couple of "clone" 1911 makers use a firing pin block. Older Colts and most other clone guns lack a firing pin safety and can possibly discharge if there is a round in the chamber and the gun is dropped on a hard surface, or if struck a blow hard enough to allow the firing pin to jump forward and impact the primer of the loaded round. By the way, Colt has just recently reintroduced new custom pistols lacking the S80 firing pin safety (called the Gunsite models) as well as a reintroduced original-style Series 70 to appeal to purists. Interestingly, the latter uses a solid barrel bushing and Series 80 hammer, so it is somewhat different mechanically than the original Series 70 models.

Regarding the controversy involving getting a decent trigger pull on a Series 80 gun, it is only of importance if the gunsmith attempts to create a super-light pull (under four pounds) for target or competition use. In defense/carry guns where a four-pound or heavier pull is necessary, the added friction of the Series 80 parts adds little or nothing to the pull weight or feel. A good gunsmith can do an excellent trigger job on a Series 80 and still leave all the safety parts in place, although he will probably charge a little more than if the gun were a Series 70 since there are more parts to work with. But any gunsmith who tells you that you can't get a good trigger on a Series 80 without removing the safety parts is likely either lazy or incompetent.


1991 vs. 1911

For those wondering what the difference is between these pistols, the fact is there really is none. Back in 1991 Colt decided to market an economy version of their basic Series 80 Government Model. The polished blue was changed to an all-matte parkerized (later matte blue) finish, checkered rubber grip panels were used, and the serial number sequence was a resumption of the ones originally given to US military M1911A1 pistols. The resulting pistol was cleverly named "M1991A1", after the year of introduction. Mechanically however they are the same as any other Colt Series 80, 1911-type pistol. Around 2001 or so Colt upgraded these pistols with polished slide and frame flats, nicer-looking slide rollmarks, stainless barrels, and wood grips (blued models only). The newer ones are commonly called "New Rollmark (NRM)" pistols by Colt enthusiasts, to differentiate them from the "Old Rollmark (ORM)" 1991 pistols. 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.
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D. Kamm