The German MP40 Versus the American M3A1 Grease Gun

Teutonic Refinement Meet Yankee Brown

World War II changed most everything about planet earth. Society, culture, industry, and politics all underwent a seismic shift during this worldwide conflict that ultimately claimed 50 million souls. This most horrible of wars spilt rivers of blood.

Previously gunmaking retained some modicum of art. Military weapons combined the machinist’s touch with the woodworker’s skill to produce weapons that were elegant, graceful, and expensive. Receivers typically began life as huge chunks of forged steel before being cut or turned into something mechanically complex, sometimes on machines still driven by steam. In the desperate fight for national survival that defined World War II, however, man perfected the mass production of his implements of destruction.

                                    MP40                                      M3A1 Grease Gun

• Weight.                             8.75 lbs                                                         7.95 lbs
• Length—Stock Extended 32.8 in                                                   29.8 in
• Length—Stock Retracted 24.8                                                      22.8 in
• Barrel Length                9.9 in                                                           8 in
• Cartridge                         9mm                                                             .45 ACP
• Muzzle velocity             1,300 feet/second                                       920 feet/second
• Rate of Fire                     500 rounds/minute                                    450 rounds/minute
• Sights                                 Fixed                                                              Fixed
• Total wartime Production 1.1 million                                          700,000

German Origins

The MP38 was cut from a heavy steel tube and can be readily identified by the longitudinal grooves cut in the receiver. The MP38 also has a dime-sized lightening hole stamped into both sides of the magazine well. Otherwise, the MP38 incorporated stamped steel fire controls, sights, and ancillary widgets. The gun also eschewed the use of wood anywhere in its production.

The MP38 was initially intended for use within and around armored vehicles. As a result, a synthetic polymer barrel rest was included underneath the barrel. The hook on the end of the rest was designed to rest outside the armor of a halftrack such that the muzzle didn’t inadvertently wander into the crew compartment under recoil.

The German MP40 submachine gun ushered in an entirely new era in military gun building. Sporting stamped steel components and a collapsible stock, the MP40 was the world’s first martial weapon truly optimized for mass production.

The MP38 rendered superb service in the hands of German Fallschirmjagers during their parachute assaults into Norway, Poland and Belgium. This tidy little submachine gun also armed German Panzer troops on their Blitzkrieg across Europe early in the war. Despite its incorporation of advanced production techniques, the Germans still saw room for improvement.

The MP40

The primary difference between the MP38 and the subsequent MP40 rested in the production of the receiver. The receiver of the MP40 was pressed out of thin gauge sheet steel on industrial presses. As a result, the gun could be produced en masse by semi-skilled labor. Production of the MP40 continued until the MP44 assault rifle supplanted it. Around 1.1 million of these guns were ultimately produced.

The folding steel stock on the MP40 was a bit flimsy yet remained effective under hard use. The pivoting buttplate must be folded flat when stowed.

The MP40 fed from a double column 32-round box magazine that tapered to a single feed for presentation. While offering reliable feed geometry, this design was prone to stoppage when dirty and required a magazine loading tool to load. The gun also incorporated a unique recoil assembly wherein nested steel cups telescoped into themselves around the recoil spring. This gave the MP40 an unusually smooth firing cycle. When combined with the weapon’s sedate rate of fire and front-heavy design this made the gun imminently controllable. The weapon was fully automatic only.

The original MP38 and early MP40s lacked a manual safety beyond a cutout to lock the bolt to the rear. However, the gun could be dropped onto its butt with a loaded magazine in place and suffer an accidental discharge. In this circumstance, the bolt might drop back far enough to pick up a round but not far enough to engage the sear. The fix for this problem involved cutting a locking slot in the front of the receiver and replacing the bolt with an improved version. The new charging handle could be snapped in place to secure the bolt in the forward position. Until the fix could be updated the Germans issued a special leather strap that would lock the bolt in place externally.

The Nazis serialized everything on their weapons to include the firing pin and these early Bakelite grip plates.

Despite the streamlined nature of the MP40 the Germans just couldn’t bring themselves to let go of their compulsive gunmaking proclivities. As a result, the MP40 is simply festooned with waffenamt acceptance stamps and every part big enough to accept one sports a serial number, to include the firing pin. This does indeed make for an elegant firearm that likely inspired confidence in its users, but did not lend itself to mass production by an industry threatened both day and night by Allied bombing. The MP40 has been encountered in action as recently as the Syrian Civil War.

The American Buzzgun

The American M3A1 Grease Gun was as utilitarian as we could make it. Sporting stamped steel for most of its components, the Grease Gun was ultimately a remarkably effective service weapon.

World War II was a come-as-you-are affair for the United States, and we found ourselves woefully unprepared when Pearl Harbor finally dragged us kicking and screaming into war. Our issue submachine gun of the day was the 1928A1 Thompson, but it was obsolete before the first bomb fell on that fateful Sunday morning. However, we Americans are a hearty lot and we responded by doing what we do best. We banded together, rolled up our sleeves, and built stuff.

The Grease Gun’s rear sight included a riveted insert to cut down on glare.

The M1928 morphed into the somewhat simplified M1A1 Thompson that was a bit easier and cheaper to build. Around 1.5 million Tommy guns rolled off the lines during the war to equip Allied forces of all nationalities. Even while we were ramping up to build Thompsons by the hundreds of thousands the War Department was rushing to secure a low-cost replacement.

The Thompson was sinfully heavy. With a loaded 50-round drum in place it weighed nearly what a Browning Automatic Rifle (BAR) might. It was also mechanically complicated and suffered simply dreadful ergonomics. Despite its shortcomings, however, American GIs loved the gun. Many to most of them had cut their teeth on Saturday afternoon crime serials and going to war with a gangster chopper held an allure. The replacement for the Thompson was as unlike this big pre-war gun as might possibly be imagined.

The Grease Gun

The front sight on the Grease Gun was nothing more than a folded bit of steel.

The M3 Grease Gun was first adopted for service just over a year after the Pearl Harbor attack. In stark contrast to the Thompson, the M3 was simple, ugly, and utilitarian. The receiver was comprised of two halves of sheet steel welded together to form a shell. The bolt rode loosely within this assembly on a pair of guide rods. This allowed the gun to function in the face of modest damage. The sliding stock was formed from heavy gauge steel wire. In the original M3 version a ratcheting lever on the right side of the gun actuated the bolt. Everything that could be produced via industrial stampings was produced via industrial stampings. When compared to the elegant and meticulously built Thompson the M3 was positively homely.

The charging handle of the M3 was found to be unduly flimsy and the unfenced magazine release allowed the magazine to be dropped inadvertently. As a result, the improved M3A1 added a raised steel fence around the magazine release and dispensed with the ratcheting charging handle entirely. In its place was a simple divot in the bolt that allowed the operator to retract the bolt with a standard finger.

The Grease Gun weighed around 8 pounds and fed from the same sort of double column, single feed magazine that drove the MP40. In the M3A1 version the wire stock incorporated a useful and effective magazine loading tool. A large stamped steel dust cover folded in place to occlude battlefield grunge. A steel tab on this appendage locked the bolt and served as the gun’s sole safety. The gun’s heavy bolt and long travel conspired to yield a rate of fire of around 450 rounds per minute.

The trigger and receiver-cum-pistol grip were all formed from stamped steel. The trigger guard was a simple length of spring steel.

The Grease Gun cost $15 to make in 1943 (around $215 today) and was quite literally disposable. The Army supply system did not stock spare parts. When a Grease Gun went down it was discarded. There was a field modification of early M3 models that involved milling a slot in the receiver for a steel charging handle that reciprocated with the bolt for use when the ratchet system failed.

Both the MP40 and the M3A1 Grease Gun were quite controllable in trained hands.

The first recorded combat use of the Grease Gun was on the Airborne drop in support of D-Day. While GIs distrusted the Greaser early on for its crude appearance, most ultimately expressed grudging admiration for the design. The gun was profoundly robust and thoroughly reliable. The improved M3A1 version briefly saw action in the closing weeks of the war. The Grease Gun was used through the Korean War and Vietnam War all the way up to the Gulf War. I encountered high mileage World War II-vintage M3A1 Grease Guns in the hands of U.S. Army tankers while I was on active duty in the 1990s.

Face Off

Both these guns are bulky. The left-sided nature of the charging handle on the MP40 means the sling must be arranged on the right. This makes the gun a bit more awkward to tote. The Grease Gun uses a standard canvas M1 Carbine sling, while the MP40 employs an adjustable leather version. The MP40 sights are flip adjustable for 100 and 200 meters while the Grease Gun’s are simply fixed, but they are comparably effective.

The two guns sport very different personalities, but I found that I could keep my rounds on target with a comparable facility with both guns. The big .45ACP bullets are fully twice as heavy as the 9mm rounds the MP40 fires, so they bring markedly more horsepower. Both weapons enjoy a sedate rate of fire so singles and doubles are easy with a disciplined trigger finger.

The MP40 and the M3A1 Grease Gun were birthed under utterly different circumstances. One nation wanted to enslave the world. The other wanted to free it. That these guns share so many similar morphological characteristics is intriguing. These days rifle-caliber carbines have displaced the submachine gun in the arsenals of most developed countries. However, for a time, these two stamped steel submachine guns slugged it out to determine the mastery of the world.

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