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Education / Training Umarex Legends MP40 BB Submachinegun: Part 2

Umarex Legends MP40 BB Submachinegun: Part 2

by Tom Gaylord
Writing as B.B. Pelletier

Umarex Legends MP40 BB submachinegun.

Part 1

This report covers:

  • CO2 effect
  • Installing CO2
  • Loading
  • Umarex steel BBs
  • Fire control
  • The sensation
  • Daisy BBs
  • Hornady Black Diamond BBs
  • Shot count
  • Hornady Black Diamonds — again
  • Bottom line

Today we look at the velocity of the new Umarex Legends MP40 BB Submachinegun. Since it has a semiautomatic mode, this will be easier than expected. However, there are special considerations for a gun like this.

CO2 effect

Most of you know that CO2 chills the gun as it is fired. And CO2 loses pressure as the temperature drops. Will that affect the velocity of this full-auto airgun? I plan to test for it. My test will show the velocity you can expect from the gun at its fastest and also what will happen as the shots happen faster and the temperature falls. There are unlimited ways of doing this, and I have selected one.

Installing CO2

The MP40 takes two 12-gram CO2 cartridges. The first goes into the magazine small end (piercing end) first and the second goes in large end first, leaving the piercing end at the top. Naturally I put a lot of Crosman Pellgunoil on the tips of both cartridges. In fact, I dumped in many drops of the oil before the first cartridge slid home, so it would already be at the bottom of the cartridge well where the CO2 inlet port is located. Each cartridge is pieced at its small end, and both must be pierced for the gun to operate normally.

The cartridges pierced silently and immediately the gas stopped all further rotation of the piercing screw. I never heard a whisper of sound — things just stopped cold. You can turn it farther by horsing it, but don’t. Once it stops it’s fine. Now it was time to load the BBs


To load the magazine you pull the follower all the way down and hold it there. Umarex should consider some means of holding the follower mechanically, because this ties up one hand full time, and since the other hand loads the BBs, you can do nothing else. I wanted to count every BB I loaded for a shot count, so I set them in the magazine channel (see photo) and pushed them into the large loading hole one at a time.

One curious note is when the follower is released, the BBs stack inside the magazine in a double-stack pattern. That is exactly what the 9mm cartridges do in the firearm.

MP40 loading BBs
The BBs organize in a double-stack pattern inside the magazine — just like the cartridges in the firearm!

Umarex steel BBs

First to be tested were Umarex’s own steel BBs. I loaded 25. The first 10 that were fired semiautomatically with 10 seconds between each shot averaged 479 f.p.s. The low was 475 and the high was 484 f.p.s., so a 9 f.p.s. spread. With the 15 BBs remaining I switched to full auto and fired a short burst, then a burst through the chronograph. The first bust registered 474 f.p.s. The second burst went 457 f.p.s. That was all I was able to record.

Fire control

I find it easy to control the firing in three-shot bursts and with care I can get just two shots. I was never able to fire just a single shot when the full auto switch was set. But I think our readers were right — no one is ever going to leave the selector set on anything except full auto.

The sensation

This is the most realistic full-auto airgun I have ever experienced! And by that I mean that it sounds like you think it should — not like a real submachine gun, but very much like one you might hear in the movies or on TV. I might have to buy this one just for that!

The recoil is also very realistic. I find it quite similar to an HK MP5 firearm — just not as much push. Even shooting one round at a time, that bolt transmits a lot of movement through the grip to the shooter.

Daisy BBs

Next up were Daisy BBs. Again I loaded 25 and shot the first 10 on semiauto with 8-10 seconds between shots. They averaged 478 f.p.s., but this time the spread was larger. The low was 465 and the high was 495 f.p.s., so a 30 f.p.s. spread. I attribute that spread more to the CO2 than to the BB.

Hornady Black Diamond BBs

The last BB I tested was the Hornady Black Diamond. Once again I loaded 25 into the magazine and shot 10 for record. They averaged 429 f.p.s. That’s more due to the gas pressure dropping than to the Black Diamond being slower, but we know that it is a larger BB. Then I shot three bursts for record — 391, 359 and 311 respectively. Clearly the gun is running out of gas after 75 shots.

Shot count

To test the shot count I loaded another 10 Daisy BBs and shot single shot. Here are the velocities.

76……….Burst — did not record!

Silly me! I left the gun on full auto. Fortunately it cycles so slow that I could count 4 shots in the first burst. Shot 80 was the 5th in the string and went out at 243 f.p.s. The next one 234 and then three that didn’t record. The last shot was at 194 f.p.s.

During this string, the bolt failed to cock after shot 85. I had to cock the bolt for each of the remaining shots. Based on this I would say there are two 40-round magazines on fresh CO2 cylinders, but the last shots will be very slow. Stick to about 70 shots if you want good power.

Hornady Black Diamonds — again

I was curious how fast Hornady Black Diamond BBs would go on a fresh pair of cartridges, so I put two more in and shot a final string of 10. They averaged 477 f.p.s. with a spread from 471 to 495 f.p.s. That’s a spread of 24 f.p.s. Now we know!

Bottom line

I would get this airgun if you have an interest in full-auto guns. This is as close as you will get to one without spending tens of thousands of dollars. You probably won’t shoot it that often but every time you do you will gather a happy crowd!

author avatar
Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

61 thoughts on “Umarex Legends MP40 BB Submachinegun: Part 2”

  1. I see that the double-stack comes into a more linier appearance the closer the bb’s come to the exit. Just an observation. This will be fun to watch at the accuracy phase. Any bets on what the yardage will be before it opens up into a 2″+ spread in full auto? How will the accuracy be in single shot mode? I guess we will all find out soon enough. I must admit, it does look like it would be a lot of fun.

    Good Day to one and all,.. Chris

  2. BB,

    I sure would like to play with one of these for a little bit. I had a chance to play with a M712 a while back. It was awesome cool. Both of them together would most definitely be over the top.

    I have noticed lately that your spell check function must not be working. 😉

      • BB

        I think these are technically typos rather than misspellings.

        Under “CO2 Effect” the word looses should be changed to loses.

        Under “Hornady Black Diamond BBs” magazine is spelled mafgazine.

        Under “Shot Count” should be “4 shots in the first burst”

        Sometimes I see these minor issues and want to correct them, but I don’t want to look like any more of a jerk than I already do. Would you prefer an email or a notice in the comment section?

      • B.B.,

        In the cooling effect section “looses” should be “loses,” but spell-check and typo features will not flag that sort of thing because it is usage, not spelling. However, RR might be referring to something else.


        • Grammarly is your friend. I use it to help proof my books. Just now, Grammarly tagged “proof.” Let’s see why…it suggests “prove,” which is in fact how the Brits refer to the act of testing firearms for their integrity. Grammarly.com. It can be a writer’s best friend.

            • Thanks, Tom. I’m kinda late to the airgun party, though I did have an “S&W” 78G more than forty years ago. Recently I acquired two airsoft M14s and a pellet M14 in support of a book on the M14. Pyramyd finally got more of those Gletcher Nagant revolvers; I bought one to use in an article on Nagant target versions that I plan to write someday.

              I’ve been reading your Shotgun News columns for years, and indeed, you are the “godfather of airguns.” I’ve learned a lot; thanks. Hmm…perhaps I should go out and shoot some of this stuff!


              Walt Kuleckk

          • Wjkuleck,

            Your books… Are you the W. Kuleck of “The M1 Garand Complete Assembly Guide,” along with its M14 and AR-15 siblings? If so, thank you for some excellent reads!


            • Guilty as charged, and thanks for the kind words! The latest work, The NEW M14 Complete Owner’s Guide, is at the printer. After final proofing, the presses will roll. That makes the ninth book. Back in ’99, I had no idea where this writing thing was going to go!

              Grammarly note: Grammarly suggested a comma after “99,” so there it is.



  3. B.B.,

    I have read user reviews that claim they can load up to 50 BBs before a jam, but who knows what they’re using? I wonder if the Black Diamond BBs, because they are so uniform in size and have that coating, might be less prone to jamming. i wonder the same about Copperheads, but because of their small size.

    It might be interesting to see if either or both of those could allow the shooter to load 55 or even more BBs.


  4. B.B.,

    Like Michael, I’m curious as to how well the magazine shoots more than 25 BB’s. I know PA said not to load more than 40 but would like to know from your testing as to what BB allows the most to be loaded in the magazine without jamming. Would also like to know if you think there might be a way to modify the magazine that would allow 60 BB’s to be shot without jamming.


  5. B.B.

    “no one is ever going to leave the selector set on anything except full auto.”

    Well then I must be the exception to that rule. Because I shoot exclusively indoors in my basement I’m hesitant to shoot this Legends MP40 in full auto. So I kept it in semi auto this past weekend. I used three separate magazines, one each for Umarex CO2, Crosman CO2, and Swiss Arms CO2. I shot slowly in semi auto, waiting a few seconds between shots but probably not as many as 8 to 10 seconds. My total shot counts were 154 for Umarex CO2, 159 for Crosman CO2, and 168 for Swiss Arms CO2. Even Tyler Patner’s Pyramyd AIR Insider video review reported more shot counts than you did.

      • I can’t comment to speed in fps because I don’t have a chronograph. When I started this airgun hobby in 2012, I approached it as much as possible with an open mind and absolutely no expectations about anything. As much as possible I have purchased airguns that I find interesting without any expectations so that I can accept them as they are and spare myself the disappointment that the gun didn’t live up to any arbitrary and unreasonable expectations. So what I’m trying to say is that, yes fps speed is important to a point, but it’s really not important to me. As you have often pointed out, accuracy is most important, and that’s important to me. Performance and reliability are also important to me. Raw speed in fps is not so important.

          • I didn’t mention this little detail earlier because I didn’t think it mattered. I have the standard version of the Legends MP40, and you have the weathered version. Although Pyramyd AIR says that both versions are rated at 450 fps, could Umarex have modified the valve for the weathered version to supply more power?

      • If you haven’t already, you might consider viewing Tyler’s review. I may have reported his shot count wrong. Or you could just call Tyler and ask him what his shot counts and fps were.

  6. BB,

    Until Umarex makes a mag with a locking follower, would it be possible to fabricobble a clip of some sort that would hold the follower down while loading? I have several BB replicas that have mags that need to be held open while loading and it is a pain. I can do it because I let my thumb and index fingernails grow long( have always relied on them as tools) but I don’t think a nail biter could even load them. A close up view of the mag from the loading port with follower to the lower end of the mag would be helpful.

      • Siraniko,

        I like to think of it as plain old ingenuity. Very few items that I see cannot be improved upon in some manner. When done well and successfully,.. that person is to be admired. Plus, you have to figure that some ideal features are always cut to save cost. I love ingenuity and greatly admire it.

        A popular term for “hack’,.. is cob-job. Not sure where that came from and if it involves the use of corn cobs,.. but I thought that the term might be of some interest to you.


      • Siraniko,

        That word is not mine .I first heard it on a YouTube channel called ” AvE.” I have stolen that one and many of his other “turns of phrase”. If you are offended by “shop talk” you might want to avoid his channel, though.

      • And the cobble part, as well as the cob in cob job, are from the trade of cobbling or making shoes. It’s like tinkering. A tinker used to travel around mending pots and pans and other things.

  7. B.B.

    Now you need pack straps on your carbon fiber tank carrier. Then add a regulated tether at 800 psi and an adapter for this little baby. A few extra magazines and those ferral can will be shredded to smithereens.

    Glad you are having fun with it. I can also see the grandkids getting one for me to store safely in my closet haha.


  8. Looks like this is an improvement on my one fullauto airgun which was an M4 airsoft rifle run on an electric motor. It didn’t sound like a machine gun, more like a typewriter. And very soon, all I noticed was how much money I was spending on ammunition.


      • Chris
        Could not resist it 🙂 took all of 10 min.
        Make the spring follower hook, pull it all the way down, bend at the bottom of the mag, not too tight, and fold up a handle to put some tension on it when installed. Will probably put some tape on it to avoid scratching the mag bottom and slipping off if bumped.
        Could actually make one up with side guides to keep it centered, or attach a small funnel with a little JB Weld to aid in loading. 😉

        I wonder if a little puff of graphite dry lube as used in key locks would help bbs’ flow better in a large capacity mags without having any negative effects on the airgun ?

        • Bob M.,

          The overloading of the magazine would bother me. Without having one, lubrication of some sort would seem to be a possible fix. A stronger spring might be another. Then again, maybe a weaker spring?

          All in all and at any rate,… nice job on a quick fix. I am sure that Umerex will be going,… DUH!,.. why didn’t we think of that? 😉

  9. Ok you all are going to stone me when I say this.

    Actually a couple things going on.

    Heres the stoning thing. Got me a .177 QB79 on the way. It’s a bulk fill bottle Co2 (China) gun. Anyway going to feed it with that Air Venturi regulated 1200 psi 3000 HPA bottle I got. Should get a crazy high shot count. Hope it’s accurate and reliable. Lots of mods can be purchased for them that’s for sure. Even a kit to change them into a repeater.

    And here’s the next thing. And maybe just as crazy as me getting a China gun.

    Got a Benjamin hand pump on the way. Going to try to boost the pump to get a faster fill time. Well it will be a balance between hard to pump and faster fill I’m thinking. Going to hook my shop compressor into the air intake filter fitting and run maybe 25 psi of air intake pressure to the pump.

    It should work. It’s going to be a balance though to get it right. Well by now you all know I’m crazy. 🙂
    But if it works. Why not.

    • GF1,

      You got me confused,… are you out of PCP or are you getting back into it? From the limited sounds of it, you sold off all of the PCP equipment and guns, short of the guns that you converted to Co2.

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