US M3 37mm Antitank Gun (Video)

The M3 was the first real anti-tank gun adopted by the US military, and it was not formally adopted until 1940 – and was thoroughly obsolete in Europe by 1942. The initial design was based on a pair of German PAK-36 guns, but in its production guise the M3 was a much simpler gun. It used a fully manual vertically-sliding breechblock (as opposed to the German semiauto breech). It fired a 1.9 pound armor piercing projectile at 2900 fps (860g @ 885 m/s), which was able to penetrate 1-2 inches of armor at 500 yards, depending on the type of shell used and the angle of the armor.

In Europe, this gun because obsolete very quickly, although it had a useful service life in the Pacific theater. It was used against light armored vehicles, pillboxes, and even infantry (with canister shot). This was also used as armament on the M3/M5 light tank (Stuart), the M3 medium tank (Lee/Grant), the M8 Greyhound armored car, and the M6 Gun Motor Carriage. It was a simple and reliable gun, just not powerful enough for antitank service. It was replaced by a 57mm gun copied from the British, which would serve until the end of the war.

I had the chance to do some shooting with an M3 recently, and it was very pleasant to use compared to other antitank guns. From behind the shield in particular, the muzzle blast was not bad at all, and recoil was minimal (note the slight rearward roll of the gun in the video, because the skids were not used). I had not expected to do any regular-speed filming at this particular shoot, and did not bring proper camera gear – I apologize for how much noise is in the background.



  1. Hey Ian, my friend….why not wait until your compatriots stop playing with their big boy toys before beginning your explanations of the subject at had…or ask them for a common courtesy extended to you…hell, they might learn something….BTW I LOVE the sound of full auto ‘stuff’ in the morning….sounds like…FREEDOM. But I heard very little of your initial setup as you were speaking between the booms & bangs. I very much enjoy your (and Karl’s) presentations both here and on Full30, to which I’m a subscriber…would LOVE to see Full 30 come to Roku…keep up the excellent work my friend…we are both lucky to live in Free States – AZ for you and FL for myself, where the only ones who look askance at gun owners are the ignorant dregs who emmigrate from the various ‘People’s Demokratik Republiks.

    CB in FL

  2. I know this might be really time consuming post-production stuff, but in cases like this, perhaps you should try to do your own ADR (Audio Dialogue Replacement IIRC)? I couldn’t hear you at all when the guns were firing off, but if you overlaid a replacement dialogue track on that part of the video, it would become way more comprehensible.

  3. 1.9 pounds seems heavy for a 37mm AP projectile. A solid steel cylinder 37mm in diameter that weighs 1.9 pounds would be just under 12 inches long. Perhaps the weight of the complete cartridge?


    Very cool video, as usual. Thanks. What are the mini gun on the left of the M3 and the big one on the right?

  5. Very nice video as usual! The M3 wasn’t a bad AT gun by 1940 standards. It fired a heavier projectile than the German and Bofors 37mm guns at a higher muzzle velocity, but of course practically all less than 50mm AT guns were obsolescent by 1942 in Europe and North Africa.

    Suggestion: put subtitles in the video so we can actually hear what you are saying.

    Little correction: should be Swedish Bofors. Most of the 37mm Bofors AT guns used by the Finnish Army were license-built copies with minimal local modifications, but Swedish and Polish made guns were used as well. The main practical difference between them were sights; Swedish and Polish guns had telescopic sights made in their respective countries, Finnish made guns had Finnish collimator sights or German telescopic sights. While telescopic sights were preferred, the line-of-sight distances in Finland rarely required engaging targets at farther the 750 meters, and of course we are talking about tank-sized targets.

  6. Here are the stats on the M3’s ammunition;

    Type Model Wt,kg (rd/proj) Filler MV (m/s)

    AP-T AP M74 Shot 1.51/0.87 – 884/870

    APCBC-T APC M51 Shot 1.58/0.87 – 884/870

    HE HE M63 Shell 1.42/0.73 TNT,39g 792/782

    HE HE Mk II Shell 1.23/0.56 TNT,27g not given

    Canister M2 1.58/0.88 122 steel balls762/752

    Target practice w/tracer
    TP M51 Shot 1.54 / 0.87

    Armor penetration;

    AP Shot M74

    0 deg meet angle(i.e. 90 deg straight-on impact);

    36mm @ 500 yards

    20 deg meet angle;

    25mm @ 1,000 yards

    APC M51

    0 deg meet angle; 61mm @ 500 yards

    20 deg meet angle; 53mm @ 1,000 yards

    30 deg meet angle, homogenous steel armor;

    53mm @ 500 yards, 46mm @ 1,000 yards

    30 deg meet angle, face-hardened steel armor;

    46mm @ 500 yards, 40mm @ 1,000 yards

    As can be seen, while the M3 was not a serious threat to German armor much after 1941, it was deadly on practically everything the Japanese had right up to VJ Day.

    Also consider that in the island campaigns, the range of engagement rarely exceeded 300 yards due to lack of visibility (jungle/terrain/etc.), therefore the short range penetration figures were the most relevant.



    • “meet angle” in American parlance is usually expressed as ‘angle of incidence’. Abbreviation is ‘AoI’.

    • “while the M3 was not a serious threat to German armor much after 1941”
      Notice that there also other armored vehicles than tanks, when the 37mm Gun M3 was useless against late-war German tank there were other viable target like Sd.Kfz. 251 personnel carrier or Sd.Kfz.231 (8-Rad) Armored Car

      • Not to mention the fact that it could quite happily penetrate the side armor of all German tanks except the Tiger in 1942. In fact it could even penetrate the 40-45mm side armor of the Panther (which did not appear until summer 1943) at close ranges, although by 1943 the towed gun was already pretty much phased out in Europe.

  7. Was there a relationship between the M3 and the M1 anti-aircraft gun that seems to have been overshadowed by license-built 40mm Bofors guns in US WWII service? Or was the caliber more-or-less coincidental?

    • According to my artillery book, the M1A2 developed by John Browning was not related to the M3. The caliber was just convenient enough for production, apparently. Anyhow, the Japanese Type 95 Ha-Go was just about a match for the M3 Stuart, able to punch it in the face just as the Stuart was able to punch the Ha-Go in return. Basically, if these two tanks were to duel, the fight boiled down to “who saw who first and shot first,” which becomes either a sniper duel or a quick-draw at high-noon.

      In any case, armor penetration isn’t a piece of cake (trust me, I recently played as a Stuart tank in War Thunder). Tank armor is more effective when the shot doesn’t hit straight on. Self-propelled anti-air units armed with auto cannons can only pray that their relatively weak main armament will at least damage an enemy’s main gun barrel to the point of ineffectiveness (upon which it spectacularly ruptures when fired).

      • 37mm guns derive originally from the 400 gram (0.88 lbs) minimum weight limit for explosive shells of the Saint Petersburg Declaration (1868). The weight of the projectile used in smallest artillery pieces at the time happened to be about one pound (i.e. they were “1-pounder” guns) and the caliber 37mm. 37mm then remained a common light gun and autocannon caliber all the way to WW2 (and in some cases beyond).

  8. I got a kick out of watching you soldier on as if you weren’t being drowned out – just a reminder that outgoing fire is not an emergency.

  9. As my interest is primarily in WWI-WWII hand held firearms I appreciate to see real action in form of cannon and howitzer. One of details which I really enjoy is the breech mechanical action and related sound in form of ‘zing’ made by loaded shot and ejected shell. Of course, laying the fire is the art by itself.

    Ian demonstrated that this gun can be fired single-handily, as he did. Good show!

    • One thing they did try was to copy the British ‘Littlejohn’ taper-bore adaptor in order to give the M3 higher muzzle velocity. According to Wiki the adaptor distorted after a few shots. This seems strange as the original Littlejohn adaptor worked well when fitted to the 2-pounder guns mounted in British armoured cars. Could this be a case of the ‘Not Invented Here’ effect?

      • Probably just poor engineering in the conversion from 40mm to 37mm, which had to be done both for the adaptor and the ammunition. WW2 seems to have suspended the “NIH” syndrome for a large degree; the US happily copied (with a license) the Merlin engine, the 6-pounder AT gun (called 57mm in US service), the 40mm Bofors and 20mm Oerlikon AA guns and that’s probably not a complete list.

  10. Yes it is underpowered and yes it is antiquated. BUT anything that is bigger than what is on your hip or shoulder is a better answer to the question. While a member of Uncle Sam’s Misguided Children, as a Swabbie friend termed us, I often was assigned to perimeter defense of 75/105/155 units and sometimes they let me play with their toys. With the older guns it was possible to deactivate the turret on tanks with a well-placed round into the “seam” between the turret base and the deck welding the turret to the body. The second round should take out the near-side track and then they were trapped in an immobilized steel coffin. Anything from a 20mm up was an option. Older 37mm Thermite/Incendiary rounds were very effective for this, but very hard to come by. Anything, including a .50 in AP with tungsten penetraters would work if you could get enough of them in the right place.

    • You are right on that count, but what if the M3’s crew got bush-whacked by a Japanese Type 97 AT Rifle team?

      • Interestingly, unlike the Solothurn S18-1000 & Lahti 20mm and Soviet 14.5mm ATRs, the Japanese considered the Type 97 to be somewhat of a failure. On paper its performance was similar, but in practice apparently not. Possibly there were some problems with ammunition quality or the Japanese simply asked too much of the weapon. For a light tank the M3/M5 had a fairly thick armor at the front, which would have made the Type 97 effective only at very close ranges. Side armor, as always, was a different thing, but perhaps the Japanese did not consider penetrating the side armor sufficient.

        Incidentally, the Soviet 14.5mm ATRs could never penetrate the frontal armor of German medium tanks, but since that was not expected of them, they were still considered reasonably successful.

        • Oops, I meant to ask if a towed M3 37 mm Gun crew got ambushed by the Type 97 ATR. Sorry about the vagueness.

  11. I seem to recall that due to the dismal performance of this gun in North Africa, there was a congressional investigation into the design.
    I wonder why the Army decided to go with a manual rather than an automatic breech.

  12. “This was also used as armament on the M3/M5 light tank (Stuart), the M3 medium tank (Lee/Grant), the M8 Greyhound armored car, and the M6 Gun Motor Carriage.”
    This gun was also used on several other American AFV, according to:мм_пушка_M3 following vehicles were armed with M5 or M6 tank gun:
    Light Tank M2A4
    Light Tank M3 “Stuart” and its variants: M3A1, M3A3, M5, M5A1
    Light Tank M22 “Locust”
    Medium Tank M3 “Lee” (as secondary gun)
    Heavy Tank M6 (as secondary gun – in common mount with 3-inch Gun M7)
    LVT(A)-1 “amtank”
    Light Armored Car M8 “Greyhound”
    Armored Car T13
    Armored Car T17
    Armored Car T17E1 “Staghound Mk. I”
    Prototype of T18 armored car (serial production T18 has 57mm Gun M1)
    Armored Car T19
    Armored Car T27
    Armored Car M38
    Armored Car “Humber Mk. IV”
    The variants of M3 gun was also used in following AFVs:
    Medium Tank T5
    Medium Tank M2
    Medium Tank M2A1
    37mm Gun Motor Carriage T42
    There exist many variants of improvised as well prototype 37mm gun mounts on wheeled vehicles, but only M6 “Fargo” enter serial production, list of prototype mounts (basic vehicle):
    37mm Gun Motor Carriage T2 (Bantam Jeep)
    37mm Gun Motor Carriage T8 (Ford 4×4 Swamp Buggy)
    37mm Gun Motor Carriage T13, T14 (Willys 6×6 Super Jeep)
    37mm Gun Motor Carriage T33 (Ford 4×4 3/4-ton)
    The 37mm gun was also mount on PT109 (vessel commanded by John F. Kennedy)

    • The Staghound was built for the British Army (which liked armored cars more than the US Army) under lend-lease and to my knowledge not used by US forces (although it was considered). The T18 Boarhound was an ambitious but ultimately unsatisfactory attempt to build a truly heavy armored armored car for the British army, which could have duked it out with German medium tanks if necessary. Humber Mk. IV was a British-built armored car armed with a US built M5 or M6 37mm gun.

      The M2 Medium tanks were used for training only.

      • AEC did a post war trade in Staghounds with AEC turrets with ROF 75mm guns and even stuck old Sherman 75mm guns/mantlets on them for Sudan. The Lebanese are probably still using them. The British army swapped the Staghound turret for old Crusader ones. Humbers used

  13. I realise this is about a weapon of historical significance. But it is maybe of value to mention that “small bore” cannon is still very much of use in today’s warfare.

    A man I knew who also served in Red Army in 80s told me: “tank without sights is just a tractor”. That reflects on way they thought and trained. As commander of BMP vehicle, he had to his disposal this ‘baby’:
    Its reach is good to 2,500m

  14. I had the pleasure of working on unexploded ordinance in Guadalcanal. Tonnes and tonnes of Japanese and American Ordinance all over the Islands. I managed to keep some I made safe. Loved the history and as we pushed out further into the jungle we could see where the Japanese were being chased off the Island and in doing so throwing their gear away.

  15. A sad thing was that the 100 or so M-3 Stuart tanks shipped to the Philippines just before the Japanese invasion arrived without any high explosive shells for their 37mms. Although the solid shot was great for dealing with Japanese tanks, there were few of those to deal with. Instead the M-3 crews were forced to try to use 37mm solid shot against both massed infantry attacks and far away anti tank guns. Needless to say our M-3 tanks therefore faired badly and many of the M-3s not destroyed in the early days when MacArthur had them parked in a cluster around the B-17 bombers soon destroyed by Japanese bombing of the airfield, soon found themselves dealing with hordes of Japanese soldiers using bayonets to pry open the hatches or building fires in the engine compartment. Not having an HE or canister shell useful for anti personnel use forced the M-3 crews to use much more machine gun ammunition than did their later contemporaries in Africa and Europe.

  16. Another issue worth adding is that when the M-3s were unloaded and put back together in the Philippines the reattachment of the M5 37mm cannon to the M-3 turret was done improperly. Since General MacArthur prior to the invasion had forbidden live ammunition practice the error was not discovered until after the invasion had begun. The improper assembly of the gun to the turret was done in a way that prevented reloading the gun after one shot was fired. The only cure was to retire to a rear position, remove the turret and the gun and re-attach everything properly, then and only then, return to battle. Needless to say, this coupled with a total lack of HE shells greatly hampered effective use of the Stuarts in the early days of the invasion.

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