The Evolution of the Ruger 10/22 Drum Magazine

By J.M. Ramos

Among the few exceptionally successful semi-auto cal. .22 ever made, was the Ruger 10/22 that truly received unrivalled attention from countless weapon tinkerers, inventors and accessory innovators. There are many gadgetries and product enhancements solely dedicated for this amazing little carbine in the past 30 years and the goodies just keep on coming. Undoubtedly, the most desirable upgrade for the 10/22 is a high capacity magazine to complement its awesome reliability, robust overall construction and military styling. Since the 1980s, there have been many attempts by independent accessory producers to fill that demand starting with the Condor 25-shot banana type magazine made by Eaton Supply. This magazine proved quite reliable but the seam of the two halves tended to split quite easily after only a few hundred rounds fired. The Condor design was eventually acquired by Butler Creek to become the new and improved Hot Lips and Steel lips magazines. Eaton Supply also produced the Sanford 50-shot drum magazine, which they introduced shortly after the Condor magazine hit the market. There are also other companies who produced other variations of hi-cap magazines for the 10/22 in the 1980s such as Ram-Line and Eagle International – both based in Colorado. Ram-Line was the undisputed leader in hi-cap magazine design at that time. Production of the 30-shot Eagle magazines without the original built-in magazine catch activator was briefly revived at the turn of the new century by a new Eagle company but has since gone out of business. Ram-Line was taken over by new management and is currently producing a new version of the original 30-shot double stack magazine and loader as well as a new 25-shot single stack. The 40 and 50-shot double stack and 30-shot single stack magazine was not revived in production. Another vintage company that produced a unique 50-shot magazine for the Ruger is the Mitchell Arms. The “teardrop” shape magazine is marketed by EMF Products. Just before the assault weapon ban in the mid-1990s, the company was bought out by MWG and subsequently produced a new version without the belt clip with improved steel magazine lip design copied from the Ruger 10-shot rotary magazine that made it very reliable. The two-tone (black and clear) aerospace polymer was replaced by an all clear fragile Lexan grade plastic material that easily cracked even during normal usage. Once the assault weapon ban sunset in 2004, many independent firearms accessory companies began producing their own versions of hi-capacity magazines for the 10/22; mostly of the banana type either in all-polymer construction or with steel lips ranging from 25-32 shot capacity to include Pro-Mag, Black Dog, HC MAGS, and Tactical Innovation who went to all the trouble of producing a CNC machined aluminium body with adjustable steel lips. Among the latest banana type magazines produced to date, it was the Ruger BX-25 magazine that tops them all in overall reliability. It worked with most brands of .22 ammo but dislikes hollow point target loads such as the Winchester X-Pert and Remington Yellow Jacket. The one magazine that can truly match the BX-25 in overall reliability in banana format is the vintage Ram-Line “Truncator” 25-shot magazine (no longer made). This particular magazine was created by Ram-Line to work primarily on truncated hollow point bullets such as the Yellow Jacket but it also functioned flawlessly with any type of bullet shape made for .22 long rifle ammunition.

In going back to our primary subject covering drum magazines for the 10/22, let us take a closer look on how each contender fares from each other in terms of design, quality of manufacture and overall reliability using varieties of ammunition. Creating a reliable hi-capacity drum magazine for rim-fire automatics is more complicated than center-fire ammunition due to its rimmed design, inconsistent tolerance in overall dimensions and power ratios from various manufacturers. In addition, correct spring tension to carry the load must work in harmony with the recoil timing of the bolt to ensure that the top round is resting on the feed lips before the bolt returns to battery. These are all factors that must be addressed in order to make it work. Perhaps the first successful rotary drum type magazine for a .22 caliber rim-fire was designed and develop in 1962 by Richard D. Casull and Kerm Eskelson for the Casull Model 290 semi-auto carbine packing an impressive 290 shots. This weapon was later re-designed by an Austrian company, Voere, in 1972 after the rights were acquired by American Mining and Development Company. The original 290-round capacity was reduced to 177 and a selective fire capability was added and was designated as the American 180 submachine gun. The secret to reliability of the AM-180 drum magazine is the way it was set up over the gun in a horizontal manner like the Lewis light machine gun. Because it feeds from the top, the spring loaded follower has less resistance and the flow of the cartridges were more consistent and smoother in comparison to a vertically mounted drum carrying a heavy weight. It has to maintain constant spring tension and correct stacking of the rims at all times during upward feeding cycle all the way to the feed lips. Any hesitation or erratic movement of the feed mechanism during the process will automatically affect the loading sequence and will result in a jam or mis-feed.

Sanford 50

Introduced in 1980 by Eaton Supply, the Sanford 50 was the first drum magazine ever offered for the 10/22. In addition to Eaton Supply, AMT also marketed the 50-shot drum magazine along with their Lightning rifle, a stainless version of the Ruger 10/22. The Sanford 50 is made of fragile clear plastic material with cast soft metal alloy feed lips that is nickel plated to conceal the type of metal used. The plating easily peeled off after just a few shooting sessions. It features a clock type spring to power its loading mechanism. The back of the magazine has an elongated window that would allow the finger to manually rotate the rotor while loading. The tension of the magazine spring gets heavier after 25-30 rounds is loaded to the magazine. When fully loaded to 50, the rotor freezes up and will not turn. With just 30 rounds loaded, the nose of the cartridge tends to nose dive when the weapon is charged and causes a jam. Five rounds are removed to allow the spring and rotor to have more play. This time the magazine fed and fired few round then the rotor freezes up and the top round stops short from reaching the lips resulting on an empty chamber. This malfunction occurred almost every other shot with failure to eject in between until there were only 10-15 rounds left in the magazine and the gun fired without a jam. The magazine will not work with hollow point bullets and only work with copper plated solid point (HV). After 2,000 rounds were fired in few months shooting intervals, the back casing suffered a crack as well as the feed lip area. This vintage magazine obviously failed in every department but it clearly represented what was yet to come.


When Eaton Supply went out of business sometime in the early 90s, the tooling and designs were said to have been sold to Pro-Mag who went to re-design the original Sanford 50 and came up with a new style drum magazine. Externally, the Pro-Mag 50 looks quite impressive, appears solid and aesthetically pleasing with its new black polymer attire. The open elongated window at the back of the shell that would allow the finger to manually rotate the rotor from the original Sanford design had been redesigned in favor of a mechanical activator in the form of an oversized knob with deep serrations. While the new set-up appears workable, the built-in activator actually made the original design more complicated so that most of the time it slips and will not engage the loading mechanism to turn when activated. A more serious flaw of the new drum is the extremely short protrusion of the lock button. The lock button secures the front end of the magazine to the receiver. While shooting, the drum tends to disengage from the gun due to this part barely engaging into place. I have added an extra length to this part to within factory specs with hopes to correct the problem but the magazine will not fully seat unless the added length of the button is trimmed down to almost to the same exact size as Pro-Mag made it. It does appear that this portion of the magazine is out of specs. The original Sanford does not have this issue. The magazine also incorporated soft metal feed lips just like the Sanford that tend to easily deform and wear out. The magazine sticks up a bit high so that the bolt drags over it slowing it down and the feed face of the bolt is hitting the feed ramp and deforming it. The magazine is difficult to load to capacity. Reliability wise, it is finicky. When loaded only halfway, it will work with an occasional jam even with solid point HV brand name ammunition. Overall, this magazine is good for decoration or wall hanging just like its predecessor.

Black Dog

The Black Dog drum magazine is yet another influence of a vintage design - the Italian made Bingham PPS-50. Among the many look-alike imports that hit the American market during the Reagan administrations, it was the PPS-50 that truly came out with the most reliable 50-shot drum magazine making the PPS-50 one of the best import in terms of reliability in firepower. During the assault weapon ban, many military styled imports were forbidden for importation into the U.S. including the PPS-50. As the demand for tactical rim-fire weapons once again came into vogue nearly a decade after the ban was lifted, the production of the PPS-50 was resurrected as the new PUMA carbine along with its original 50 and 30-shot steel magazines. My experience with the vintage PPS-50 drum magazine is quite pleasant in terms of overall reliability out of the box that works with virtually any brand and type of ammo as long as it is high velocity. The loading operation of the drum was never an issue as long as the clock type spring tension is set up correctly. The secret to the drum’s outstanding reliability is the use of dummy cartridges as a follower. These dummy cartridges are looped together using a special elastic band to allow the follower to be stretched and glide smoothly following the contour of the magazine from the first to the last round. The only drawback to this arrangement is the use of a rubber material that will eventually snap and separates the dummy cartridge followers. Despite this flaw of the design, the magazine will still function as long as all the dummy cartridges are present to the magazine prior to loading the actual live rounds. After all the ammo was fired, the top dummy round will be chambered indicating the magazine is empty. Simply eject the chambered dummy round and put it back to the magazine and reload.

The Black Dog version for the 10/22 follows the same arrangement using dummy rounds as follower and elastic to keep them together. The only difference is the overall construction with the PPS-50 using the old world tradition of steel material while the Black Dog with modern indestructible type plastics. Although similar in overall mechanical characteristics, the PPS-50 magazine proved to be more reliable overall. In closely studying the design format between the two drums, I found some very interesting results. It is my conclusion that the use of steel material appears to be more compatible in this particular arrangement using rimmed ammunition. During live fire test of the Black Dog drum, the cartridge (solid or hollow point) being stripped from the feed lips tends to pivot upward as it hits the tip of the feed ramp and jams the closing of the bolt on an empty chamber with the lower half of the cartridge still lodged in the magazine. This problem can be attributed to the internal cut out that is supposed to guide the cartridge rim at an angle after the nose hits the feed ramp but instead allows the round to rotate backward instead of forward. In closely examining this area of concern, it was noted that there is a visible sign of drag marks and dents to the guide shoulder caused by the cartridge rim that virtually deformed the shape of the cut out that may have been causing the round to alter its course during the loading process. Black Dog should have opted instead for a plain internal wall of the tower (just like on their AR drum tower) so there is less to go wrong. The space of the magazine (front and back) will also need to be increased to allow more room for smoother upward movement. Most of the jams happen inside the tower indicating tight tolerance in this area for some ammunition even with the spring tension increased. The feed ramp may also need redesigning to minimize the tipping of the bullet nose during loading and also to accommodate hollow points. Deformation of the internal cut outs would have been avoided if the magazine tower is made of steel like the PPS-50. In addition, there are also many ejection problems caused by the magazine’s narrow ejection shoulder. I have corrected this issue by simply filing off the narrow ejection shoulder and level it off with the lower step of the feed lips that holds the top round in place to let the factory ejector do its job. Another problem that must be addressed in the Black Dog drum design is the single hole in the rotor that connects to the follower pack. This part also controls the tension of the rotor spring depending on how you set up the follower. The spring tension is pre-calculated from the factory. However, I found the spring with not enough tension to adequately power the rotor and freezes up on occasion leaving an empty chamber. This problem can also be contributed by the tight tolerance for cartridge length inside the tower. There should have been at least two or three holes in the rotor for the follower pack in order to fine tune the spring tension. The way it is set now, you have to rotate the rotor a full 180 degrees to increase the tension (nothing in between) to increase spring tension. With too much spring power, the rotor is difficult to rotate and load the magazine to full capacity and will require a stronger recoil spring for the bolt to match in its timing. The housing and tower of the magazine is made of tough polymer material. However, the two small side ears where the assembly screws that connects the two halves have easily cracked. I have 5 of these drums and all of them have the same issue. This area of concern must be beefed up to minimize or eliminate the problem. I found the CCI Blazer to work best with this magazine although the company also recommends Federal and American Eagle brands solid point HV ammo. Overall, the Black Dog drum has the right idea but definitely needs more refinement in the above noted areas.

GSG 110

Not too long ago, German Sports Gun (GSG) introduced a 110-round drum magazine for their very popular GSG 522 series of carbines and pistols. This revolutionary magazine system is slated to be offered also to their AK47 .22 and eventually for the Ruger 10/22. Finally, in 2014, the GSG drum magazine for the 10/22 has arrived; one for U.S. consumers and the other for the Canadian market. Both appear to be identical except for market destination markings. The main body of the GSG 110-round drum is made of black aerospace plastic material while the actual tower is made of cast aircraft grade aluminum. The top of the tower utilized a stamped inverted “L” piece stainless steel feed lip mounted to the left side of the tower secured into place by a solid pin. The “L” piece also acts as an ejector. This is one simple but very clever idea and it works. The only part on the GSG drum that differs in accommodating all the three guns noted (GSG5, AK47 .22 and 10/22) is the tower design and width, with the 10/22 being the widest. The height of the tower is perfect for the GSG5, but it sticks out for the AK47 .22 and 10/22. However, in the case of the Canadian made FS556 tactical chassis for the 10/22, the height of the tower just is perfect, as if it was tailored for it. Another notable feature of the drum is the excellent fit to the magazine chute. There is barely any minimal play once it is inserted to the gun. This is a good feature particularly with an ultra-hi-cap magazine that can result in a more consistent less interrupted feeding operation that contributes to overall reliability.

Just like the Bingham PPS-50 and Black Dog drums, the German made magazine made extensive use of dummy rounds in its overall loading system. Charging the GSG drum is one pleasant surprise. Despite its amazing room to accommodate 110 rounds, the tension of the spring is the same from start to finish – a true constant force spring system, truly a remarkable feat for the German gun maker. So far, the only major drawback of the design is the loading process. Loading the magazine is a bit tricky and will take some practice to get used to. The trick is not to force the ammo if it hesitates to go in while turning on the loading disk. Once you have encountered this problem, unload all the cartridges and start all over again. The first 10-15 round is the most critical as the live ammunition is just passing the bottom corner of the tower and the loaded cartridge is being lined up toward the side pocket of the drum. As soon as you pass this stage and the loading disk rotates freely and smoothly, the magazine can now be loaded to full capacity without any interruption. The magazine has four windows allowing you to see if the rounds are properly spaced out. Failure to do so can result in a jam. Best to repeat the procedure and make sure the rounds are spaced out properly. For best result, load only 100 rounds and leave enough room for spring play. GSG highly recommends using the CCI Mini-Mag copper plated hollow point ammunition for optimum performance. Indeed, this ammo performed best in my test. However, I also got excellent result with cheaper Winchester 555 copper plated hollow point bulk pack and Federal Champion 36 gr. Copper plated hollow point. Looks like the GSG drum prefers hollow point over solid point, something U.S. made drums are prone to jamming. This drum magazine is truly a marvel of engineering and design, something German gun makers are famous for. GSG has truly accomplished a goal many gun tinkerers in the past three decades had hoped to create for the 10/22, but failed to deliver or have no clear idea how it is done. Finally, the quest for the ultimate firepower upgrading for Bill Ruger’s masterpiece .22 has become a reality at the peak of the tactical rim-fire gun market in the 21st century.



This article first appeared in SmallArmsReview.com on February 28, 2014


Comments have not been generated for this article.