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Reloading and Accurizing for the 45 Colt Revolver – Part 1, by “Papa Bear”

The 45 Colt revolver is an excellent weapon with many great characteristics. This big revolver is fun to shoot! It throws a big bullet, around 250 grains, but does not have the snappy punishing recoil of larger magnum handguns. Often referred to as “the original magnum revolver”, the old revolver cartridge was a hit when it was introduced. The heavy lead bullet with large frontal area proved to be big medicine against both game animals and ne’er do wells caught on the wrong end of its muzzle. Being eclipsed by newer and higher velocity magnum cartridges has not diminished the deadly abilities that made the 45 Colt initially so popular. The strong single action design, combined with a comparatively lower pressure round, yields an excellent and long service life, virtually ensuring the revolver will still be usable even after its owner is not. Partially due to SASS competitions, partially due to preppers, partially due to reloaders, and partially due to western movies, the 45 Colt revolver has seen a resurgence in popularity. It’s thrilling to see this old weapon come alive again. However, some manufacturers have less than stellar out of the box accuracy, which is a powerful killjoy. The following is an explanation of how to do a couple of easy home gunsmithing procedures to correct impediments to accuracy within the weapon, some reloading advice to address the problems causing poor accuracy with new production factory ammunition, and a few tips to maximize time at the shooting range.

45 Colt revolvers are produced in factories using machines that have cutting tools and other parts that wear out. This fact, combined with fatigue and human error, means there is plenty of room for discrepancies in precision, tolerances, and finishing details. Anyone who has worked in a factory or on an assembly line can attest to differences in products made at 9:00 Monday morning and those made at 4:59 Friday afternoon. These little inconsistencies in finish details are easily corrected. There are three things that the home hobby gunsmith can easily and quickly do to correct accuracy problems that may be originating within the weapon. These three fixes are chamber throat reaming, barrel lapping, and muzzle lapping. Chamber throat reaming is a correction made by using a special cutting tool to remove some material from the inside the cylinder’s chamber where the bullet travels through the cylinder and into the barrel. This operation sounds difficult and daunting, but it is not either and is well within the ability of the kitchen table hobby gunsmith. Barrel lapping is a method used to smooth and polish the bearing surfaces of the barrel’s riflings. Lastly, muzzle lapping is used to deburr, smooth, and polish the end of the barrel where the muzzle was cut. These three tasks will be explained in that order, from the most time consuming to the easiest, and will seem like a walk in the park after reading the following explanations.

Chamber Throat Reaming

One very problematic design flaw in new production 45 Colt revolvers from earlier years was an improperly cut and undersized chamber throat. This is remedied by chamber throat reaming. If the portion of a revolver barrel closest to the cylinder is examined, the inside of the barrel is machined to have a slight conical shape. This is to assist the bullets transition across the cylinder gap and into the barrel and to help achieve proper bore alignment. When the chamber throat is undersized, the bullet is swaged as it passes through the end of the cylinder. The bullet is then forced to expand again, as it passes out of the cylinder, by the pressure of the propellant. When the bullet enters the closest portion of the barrel, the slight conical shape squeezes and swages the bullet once again. This squeeze-flatten-squeeze cycle can place the bullet in less than optimal alignment relative to the axis of the bore and understandably has a diminishing effect on accuracy. To correct this, the major online reloading and gunsmithing supply retailers sell a proper 45 Colt chamber throat reamer with a set of pilot bushings. The pilot bushings are used to keep the tool properly centered during the cutting process. Any “T” handle that can be used to hold a tap will work to hold the reamer. To begin, ensure the chambers are clean. Insert the pilot bushing, apply some cutting oil to the chamber and reamer, and turn it with even pressure. Repeat the reaming on each cylinder. Do not be afraid to do this. It is the most intimidating operation in this article to perform, but it is well within anyone’s ability and will drastically improve the accuracy. With the chamber throat reamings done, the other two procedures are a breeze.

Lapping the Barrel

The next step it to lap the barrel. Lapping the barrel will help to smooth out any tool marks, scratches, uneven places, or imperfections in the riflings. Doing this will require valve lapping compound [1] and a good steel polish [2], both of which are available at any auto parts store. Start by thoroughly cleaning the barrel of the disassembled revolver. After the bore is cleaned absolutely spotless and a folded oiled patch on a jag can be pushed through the barrel without a single mark being left on it, it is time to lap the barrel. Start by taking a cleaning patch and folding it until it fits snugly in the bore with a brass jag. Next, apply the valve lapping compound to the patch where it will contact the bore. Make a consistent number of passes with the lapping compound. (Ten is an easy to remember number of passes.) Then, wipe out the bore with the jag and a patch with gun oil [3]. Inspect the bore. The goal is not to grind the bore out of specs. The goal is to achieve a shiny and glassy appearance to the bore. Repeat using the lapping compound as needed. To complete this process, take the metal polish and polish the bore until it shines like a brilliant mirror. End the barrel lapping by cleaning out any residue and applying a penetrating gun oil. A slick, smooth, and burr-free bore will make for a more accurate weapon. After lapping the bore, it is time to move on to lapping the muzzle.

Lapping the Muzzle

The last and easiest step to increase accuracy is lapping the muzzle. Lapping the muzzle is accomplished by deburring, smoothing, and polishing the end of the barrel, where the last part of the bore contacts the bullet as it leaves the muzzle. Often, there are small burrs left at the end of the barrel and the end of the rifling where the barrel is cut to length and the muzzle contour is cut. These small burrs can affect the bullet flight as it leaves the muzzle. To correct this and erase any burrs, purchase a brass dome headed screw that will fit partly into the bore while contacting just the inside of the muzzle. The size of the screw will vary slightly depending on the way the muzzle is cut. So, it is best to purchase several different sizes of screws and save the unused ones for future projects. After testing the different screws by holding them against the muzzle, select the screw whose head protrudes partly into the bore but contacts only the inside edge of the muzzle. Inspect the screw head for burrs or malformations, and correct any with a jeweler’s file. Next, place a small amount of lapping compound on the screw head. Tighten the screw into a drill chuck. Place the screw against the muzzle and use the drill to polish the end of the riflings. Clean and check the muzzle after every 10 to 15 seconds. The goal is to see a visible shinny ring appear on the edge of the muzzle. The shiny ring only needs to be thick enough to be visible across the lands and grooves at the muzzle. It is not necessary or advisable to completely recontour the muzzle. Clean the muzzle and remove any lapping compound. Then, use the same metal polish to finish polishing the newly smoothed area. Lastly, clean with some penetrating gun oil. Lapping the muzzle removes burrs and rough spots that can cause erratic bullet flight and greatly improves accuracy. After finishing this quick and easy task, it’s time to get the most out of handloading the 45 Colt.