Colt Single Action Army


The First Generation Colt Single Action Army revolvers were produced between their introduction in 1873 and WWII.  Production resumed in 1956, and these guns are known as “Second” generation Single Action Army revolvers, which are quickly identified by a “SA” suffix at the end of their s/n, and continued through 1975.   In 1976 a “Third” generation of Colt Single Action Armys was introduced.   On these, the “SA” marking is moved to the front of the serial number.

These guns carried a varied number of names, from 1873 for the year it was introduced.  The Peacemaker was another name used by the old west community.  Single Action Army was what the military used when the guns were issued to the cavalry.  The factory even today uses model designations of the alphabet & this model was the “P”.

Calibers & Configurations:

The .45 Colt chambering was by far the most popular, accounting for nearly half of the pre-WWII SAA’s. The “Winchester Centerfire” calibers – .44 WCF (44-40), .38 WCF (38-40), and .32 WCF (32-20) placed 2nd, 3rd & 4th in popularity; doubtless in part due to the fact that paired with an 1873 or 1892 Winchester they allowed the usage of the same cartridge in both rifle and revolver, simplifying supply logistics.  The obsolete .41 Colt was the only other caliber produced in significant quantity, although a number of other chamberings were available on special order.  Other calibers as 38 Special & 44 Special were among those included.   Standard barrel lengths were 7-1/2″, 5-1/2″, and 4-3/4″, with others available on special order.

Special guns made without ejector rods or housings were called “Sheriff’s Models” or “Storekeepers Models”, and often had shorter than standard barrels. The SAA was used by the US military from it’s introduction through the Spanish American War & Philippine insurrection. The original 7-1/2″ barrel martial version is called the “Cavalry Model” by collectors.  Many military SAA’s were refurbished by Springfield Armory or Colt for reissue with a shorter 5-1/2″ barrel, and these are called “Artillery Models” today. The Bisley model was introduced in the 1890’s, and featured a redesigned grip & hammer.

Later in the 3rd generation series the New Frontier was introduced with a more squarer top strap of the frame for accommodation of adjustable rear sights plus a ramped base & front sight.

Colt SAA-S1

Colt model 1873, also known as the Single Action Army, or the “P” model at the factory. This gun happens to be a 1st Generation


The threads on the 1st & 2nd generation guns used a 20 thread per inch threads.  On the later 3rd generation the barrel threads were changed to a finer pitch.


Also the cylinder ratchets were made differently, thus requiring other component parts that mate to & function with the cylinder to be also altered. The new cylinder eliminated the integral base pin bushing.  When we refer to Old Style or New Style, we are actually meaning the Old Style as being either the 1st or 2nd generation, while the New Style as the 3rd generation.

Bolts / Cylinder Stops:

The technical factory name for these parts is a “Bolt” or probably a locking bolt.  Many non gunsmithing persons call them a cylinder stop.  This part was used unchanged until 1976 when the 3rd generation version was brought out.  The original part number was #50976.  After the change the part number was not changed, but the configuration of the part did.   It was simply designated the “Old Style’ or the “New Style”

Listed below are the various styles encountered.  Those of you who are trying to find a replacement part for the aftermarket “Clones” may well have to take the firearm in question apart & compare the broken part with these CAD drawings of the Colt SAA.  The Old Style & New Style are exact replacements for the Colt firearm.

Old Style
#50976 OS
New Style
#50976 NS
 Colt_OS  Colt_NS

These bolts are made in a standard thickness of .152.   Wisner’s Inc. makes an oversize thickness of .160 to be used on old worn cylinder locking notches.

All of these parts need to be hand fitted to the individual firearm.   They are not just a drop in part, even the factory replacement parts were not.  The RH tail need not be fitted, other than stoning the back side to allow it to function smoothly.  The inner (LH) tail end needs to be fit to the hammer stud so it is timed to slide off the stud’s angle as the hammer is cocked, just as the cylinder is rotated with the locking notch in line with the bolt at the full cocking motion of the hammer.

Once the bolt is in line with the cylinder notch & the bolt’s tail slips off the hammer stud, the bolt’s inner radiused face will drop into place with the hammer’s stud now that the hammer is rearward & locked into the fire sear notch of the hammer.

Before all this can take place, the hammer has to have proper sear notches, & the stud has to be correct for timing.   The trigger also needs to be in good shape to mate with the hammer notch for proper timing.  Also the cylinder base pin & bushing need to be fitted so not excess slop is there for endshake looseness.


The hands were also changed at the 3rd generation as shown below.

Old Style
New Style
 Colt_S1000  Colt_S2770

Sear & Bolt Spring:

The sear & bolt spring is as flat, dual tailed spring held in place by one screw.  It places tension on both the trigger & the bolt.  The original thickness of this spring is .045.  Aftermarket springs of  a medium strength are made in .035 while a light weight version is made in .025.  The .035 would be the common one used to lighten up the average shooter firearm.


The mainspring is a flat arched leaf spring that has a slight groove on the upper forward end for the hammer roller to ride in.  The original material was .062 thick & machined to a taper (top to bottom) to make it like a buggy whip for the 1st & 2nd generation guns.  The 3rd generation saw the same spring, but no taper, making it a heavier pull on the hammer.

Replacement mainsprings are usually made slightly long so they can be fitted to about any version, even the many copies or clones.  If they are not properly fitted, when the hammer is pulled to the rear to full cock, the front tip section may bind in the inner arc of the hammer & create a stiff resistance because it is being stopped by the mainspring front.  This situation makes for a hard cocking firearm PLUS it can very well break the tip off the mainspring.

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