In the history of detachable magazine-fed firearms, we’ve seen a lot of interesting and unique takes on the idea, from odd magazine designs like pan mags to various magazine mounting positions. We’ve looked at odd and interesting magazines in the past, but today we are looking at where the magazine is mounted on the gun: bottom, side, and top.
Throughout history, each has shown its strengths and weaknesses. Today we are going to dive into the pros and cons of each style, as we’ll discuss the historic reasoning behind the placement of magazines. We’ll also provide a modern example of at least one type to show just how far the concept has come.
The War is Over — Bottom Mounted Magazines Won
Yeah, it’s fairly apparent that bottom-mounted magazines won this war. This has become the de facto position for mounting magazines for every modern rifle, SMG, and even magazine-fed shotguns. Mounting the magazine to the bottom of the gun makes sense for an individual weapon.
Historically this method has been used since firearms have had removable magazines and even prior to that. Early bolt action repeater and, arguably, lever action guns also, used fixed magazines mounted to the bottom of the gun. When we entered the modern era, this style proved its dominance. By World War 2, it was on the upswing, and shortly after the end of Korea, the removable, bottom-mounted magazine was clearly the future of arms design.
As we shifted to belt-fed squad support weapons and modern battle rifles, the need for any other method shrunk. Sure, plenty of guns were used beyond this point with side and top-mounted magazines, but they were clearly oddities for the era and often out of date.
Pros and Cons
The magazine is placed in a position where it’s easier to reload and reach. Reloading, in particular, is very ergonomic and intuitive. The magazine is easy to remove and replace without having to even come off target in most positions. Also, gravity is on your side with modern rifles like the AR 15. Press the button, and the magazine removes itself.
The magazine stays out of the sight line and keeps the rifle profile slim and lithe for easy maneuvering through a big world. Every serious modern design uses the bottom-mounted magazine.
Modern intermediate cartridges strike a great balance between size and capacity. A 30-round magazine is not that long compared to a 30-round magazine of .303 or .30-06.
The only downside is the shooter can’t achieve the lowest possible prone with a bottom-mounted magazine. Also, reloading in the prone isn’t as easy. Still, it’s completely doable, and with modern weapons isn’t a significant issue.
Top Mounted Magazines
Top-mounted magazines are exactly what it sounds like. They sit on top of the receiver and feed downwards into the weapon. These are the inverse of the bottom-mounted magazine and were fairly common in a post-World War 1 world. Mounting the magazine to the top of the gun made a lot of sense in this early modern war.
In the first World War, the belt feds were not exactly man-portable with their tripods, water jackets, and overall weight. Portable firepower came down to what is aptly called machine rifles. These are magazine-fed weapons, and placing the magazine at the top was a smart move for the time.
While these were light machine guns, they were still heavy, and automatic fire is always best supported by bipods. The weapons needed fairly large magazines for their fairly long cartridges, and they would be difficult to use in a prone, bipod-supported position. Additionally, the big hanging magazines would get in the way when the weapons were sued in the trenches. Along the way, top-mounted magazines did move to a few submachine guns.
Pros and Cons
The biggest pro would be that these magazines allow a machine gunner to get a nice low-prone position to lay waste on the enemy. These magazines could hold anywhere from 30 rounds and up with no maneuverability issue in the prone. In the machine rifle context, an assistant gunner could also load the weapon much easier from the top.
Even if a gunner is handling the gun by himself, the gun is likely in a supported prone position. This still makes it easier for a single gunner to reload the likely very heavy weapon. Also, gravity helps the gun feed as it works with nature, instead of against it.
The downside of the top-mounted magazine is that it doesn’t translate well for anything other than the outdated machine rifle concept. It’s not as ergonomic or as intuitive for a rifle or SMG. Your sightline is also blocked, resulting in side-mounted sights or very high sights.
A relatively modern example of this concept that works is the P90 and PS90 series of firearms. Their example of a top-mounted magazine is rather odd and does break from tradition.
Side Mounted Magazines
Side mounted magazines are another invention that came out of World War 1, at least the modern examples of these guns. A side-mounted magazine sticks out either the right or left side of the gun. However, the most common has always been with the magazine sticking out the left side of the gun to accommodate right-handed shooters.
The most notable examples of this design are SMGs. Specifically the MP18 and MP28 as well as the Sten gun. The origin of the side-mounted magazine comes from the Mp18 and later MP 28. The Germans designed the original MP18 for their newly founded stormtroopers, and the magazine placement was to help the troopers fire around the top of a trench.
Later as World War 2 broke out, the Brits desperately found themselves needing a submachine gun. So, they essentially ripped off the MP28 but in a very cheap way, and that includes the placement of its magazine.
Other notable weapons that used a side-mounted magazine were the Johnson LMG and the FG42, which were not submachine guns.
Pros and Cons
Much like the top-mounted magazines, a side-mounted magazine allows the shooter to get nice and low in the prone. For guns like the Johnson LMG, this allowed them to lay down a lot of support fire in a low prone position. Also, A-Gunners could also reload a side-mounted LMG easier than a bottom-loaded magazine.
Shooting over cover and out of trenches is easier with a side-mounted magazine as well. However, that isn’t a huge concern these days.
The downsides are a weapon that’s essentially three times as wide as it needs to be. That might make things tricky going through small entrances and locations. The ergonomics are extremely awkward, and Lord forbid the shooter be wrong-handed.
Modern examples of this are rare, and the only one that I can figure out is the M249 SAW. Specifically the American M249 and not the Minimi. This is traditionally a belt-fed weapon, but there is a magazine well on the left side to feed STANAG Mags into.
Loading Up and Going Bang
There are numerous solutions to solve a common problem, and obviously, one particular method excels above all. The side and top-mounted solutions are products of their time and technology. They were certainly applicable solutions at that time. These days it’s belt fed, or bottom mounted, but I find it interesting to see how far we’ve come by looking back at previous designs.
