Umarex Legends M3 BB Grease Gun Review


Testers: Doug Wall, Stephen Archer

Caliber: .177 cal. BBs

Model Number: 22561822

Test Date: Jan 2, 2023

Serial Numbers: DEO 17518

Source of Supply: Supplied by Umarex USA

Condition: New

We Like

Fantastic realism!

Strong Muzzle Velocity.

Excellent accuracy.

We Don't Like

Incredibly heavy trigger.

Needs care loading BBs.

Nothing else.


  • Value for Money
  • Comparison to Makers Claims:
  • Consistency
  • Appearance and Finish
  • Buying and Owning
  • Realism, Look & Feel
  • Realism, Trigger Action
  • Accuracy & Point of Aim
  • Shot Count
  • Muzzle Velocity



The Umarex Legends M3 BB Grease Gun is an outstanding airgun. If you’ve ever wanted an original M3A1, this one’s for you!

The HAM team liked almost everything about it. We recorded good accuracy and strong velocity for a BB gun. The primitive sights match those of the firearm, but are good enough for consistent hits on feral soda cans at 10 yards, and probably further.

Of course, the full auto capability gives about the most fun you can have with your clothes on! It’s great fun to “hose” the target and we challenge anyone not to be smiling broadly after doing so.

We’d prefer a lighter trigger and the magazine needs a little care in loading. But overall, this is an easy HAM Gold Award winner that will provide a ton of fun for a ton of people!


At 1 Cent short of $200, the Umarex Legends M3 BB Grease Gun is excellent value for such an accurate reproduction, selective fire model. Although a new introduction, it’s actually selling today for $25 less than the Legends MP40 and $50 less than the Legends Thompson.

Umarex Legends M3 BB Grease Gun Review

There’s going to be a huge number of military enthusiasts and airgunners who will love to own and shoot it with no complicated Federal paperwork. Oh and the price is waaaay less than the astronomical price of an original – if you can find one, that is…

This is a no-brainer for value for money!

Legends M3 CO2 Grease Gun 0.177



There’s no doubt about it. The M3 BB Grease Gun is right up there for realism with other Legends products such as the M1A1 Thompson and MP40. That means that it a very, very close replica of the original centerfire model.

At about 7 Lbs 11 Oz, the BB Grease Gun is just about the same as the weight of the original when unloaded. The overall size is similarly close to that of the firearm.

Yeah, I know it’s too cold to shoot CO2-powered airguns outside. But at least we can take photographs!

Umarex Legends M3 BB Grease Gun Review

Balance is great and the gun feels extremely solid and realistic in the hand. The two position (either “in” or out”) wire stock provides a surprisingly solid support when extended. It’s even possible to get some sort of cheek weld although the original was never intended to be a precision long range shooting tool, after all!

The Grease Gun continues with the highly desirable Legends trend of making the obligatory “NOT A TOY etc…” printing as small and inconspicuous as possible. In this case, it’s on the right side of the magazine well.

Umarex Legends M3 BB Grease Gun Review

The few controls of the original are well-replicated – that’s the magazine release above. The only difference is the safety/fire selector switch that’s similar to that of the Legends MP40 and located quite-inconspicuously on the underside of the action, ahead of the trigger guard.



The M3 BB Grease gun tested by HAM shot about 1 1/2-Inches left and slightly high at 10 Yards. This tendency was observed with all of the standard HAM test BBs, as you can see from the test targets at the foot of this review.

Given the realistic (primitive) non-adjustable iron sights, there’s no easy, non-invasive way to correct this.

(Were this our gun, the HAM Team would remove the screw-on rear sight and very carefully elongate the screw hole with a needle file so that it could gain the small amount of windage change necessary. We would probably try this rather than try to tap-over the brittle-looking, cast front sight. But don’t blame us if you try this and end-up with problems!).

Then there are the two non-invasive windage correction methods. Just aim off a little to the left, or keep on firing on full auto and pivot slightly until you’re hitting the target. The latter is clearly the most fun…

At 10 Yards, HAM Tester Doug Wall was able to keep every shot within the size of a soda can when fired on semi-automatic. That’s in spite of the incredibly heavy trigger and the fact that the Grease Gun fires from an open bolt. Great shooting, Doug!

Of course, Doug could not resist trying a 60-shot, full magazine “dump” on full auto. The results are shown in the test target below.

M3 BB Grease Gun

So – in spite of that 14 Lb trigger and the hammering action, Doug was able to hold the overwhelming majority of the BBs within the size of a soda can at 10 Yards. And those that missed, didn’t miss by much.

That’s pretty impressive, plus being a ton of fun! The hammering and jumping of the gun under fires are benefits, of course, as the blowback adds to the enjoyment.



The manufacturer claims a maximum Muzzle Velocity of 450 FPS for the Umarex Legends MP. That’s what it says on the box and in the instruction manual. This is nearly 30 FPS higher than the 423 FPS maximum achieved in the cool – 61 degrees F – HAM test ranges.

However, HAM tests on CO2-powered guns indicate that the Muzzle Velocity increases by about 2 FPS per degree F change in temperature. This means that the M3 BB Grease Gun will shoot at the claimed 450 FPS at a temperature of about 69 degrees F.

Extrapolating from these numbers, the Muzzle Velocity will reach around 514 FPS if the gun is at – and is fired in an ambient – temperature of 90 degrees. So it’s clear that the Grease Gun tested by HAM has the capacity to blow away the manufacturer’s velocity claims in warm weather.

Umarex Legends M3 BB Grease Gun Review

Umarex USA says to expect about 120 shots from a pair of 12 gram CO2 cartridges. The gun tested by HAM delivered either 70 or 150 shots per fill. Huh???

We’ll explain this further in the “Shot Count” section of this review below…



With an average Standard Deviation of 11.51 FPS across the range of standard HAM test BBs, the Legends Grease Gun was not the most consistent we’ve tested. In fact, it was less consistent that the Thompson and MP40.

However, it’s still good enough for the purpose at hand and – as can be seen from the test targets – didn’t prevent some pretty good accuracy at 10 yards in Doug Wall’s hands.



Overall, the trigger and action of the M3 BB Grease Gun tested by HAM were very realistic, except for one thing…

The trigger pull weight was waaaaaay above the 5 – 7 Lbs listed for the firearm. At around 14 Lbs, it’s probably the heaviest trigger we’ve ever experienced. In fact, the pull weight was so high that it exceeded the range of our Lyman Digital Trigger Pull Gauge and Doug Wall had to resort to using a luggage scale instead!

That pull weight really is unacceptable, particularly as the Legends Thompson gave a trigger pull weight of around 7.5 Lbs.

Returning to more positive aspects, the cocking system was very faithfully reproduced. The ejection port dust cover is first raised, then a finger or thumb is inserted into the hole and pulled back to cock the action. Snap the dust cover back down and you’re ready to go!

As mentioned previously, the M3 BB Grease Gun is fitted with a combined fire selector/safety switch ahead of the trigger guard. This is unobtrusive, functions well and clearly is a good thing to have for safety.

In use, the Grease Gun’s blowback action certainly “hammers away” when firing full auto – particularly with full CO2 cartridges. The action locks open once the magazine is empty to avoid wasting CO2 – another nice and effective feature.

If we’re going to be really, really picky, it’s worth note that the cyclic rate of the M3 BB Grease Gun is 1,050 rpm – according to the manufacturer. That’s a lot faster than the 450 rpm of the firearm, but this observation is offered as a comment only, not a complaint.



This is interesting! When shot deliberately in semi-automatic mode, the M3 BB Grease Gun tested by HAM delivered 70 shots per pair of 12 Gram CO2 cartridges.

In full-auto testing, we recorded 150 shots before the action ceased cycling.

There’s only two possible explanations for this. Possibly the gun somehow uses less gas per shot when in full-auto mode. This would result in a corresponding fall in the Muzzle Velocity, of course. However the chronograph would not record the full auto shots, so we can’t prove that.

The only other possibility is that we had one un-filled CO2 cartridge installed for the “deliberate” testing. Both cartridges were new and both were pierced when extracted after testing. But new, empty 12 Gram cartridges are not completely unknown.

Given the outstanding shot counts of the Legends MP40 (150 shots) and Thompson (218) shots in HAM testing, we’re going with the latter explanation!



The Legends M3 BB Grease Gun was tested at a temperature of 61 degrees F. This is important to know as  – like all CO2-powered airguns, the Grease Gun shoots faster in warmer ambient temperatures.

BBsAverage Muzzle VelocityAverage Muzzle EnergyAccuracy
Crosman Copperhead 5.13 Grain423 FPS2.04 Ft/LbsPoor.
Umarex Steel 5.29 Grain419 FPS2.06 Ft/LbsExcellent. Best Tested.
ASG Blaster 5.32 Grain413 FPS2.01 Ft/LbsExcellent.
Hornady Black Diamond 5.36 Grain418 FPS2.08 Ft/LbsExcellent.
Daisy Avanti 5.44 Grain427 FPS2.20 Ft/LbsExcellent.

Taking the test temperature into account, the Grease Gun tested by HAM was slightly “hotter” than the Thompson and MP40 samples we’ve reviewed previously.



“Very nice! True to the original,” Doug Wall wrote in his test notes.

There’s no doubt that it’s very tough to fault the overall appearance and finish of the Legends Grease Gun.

Overall, the level of detail and accuracy built-in to this replica is truly amazing. The only real giveaway – apart from the printed markings – is that the right side of the gun shows how it’s assembled using screws. Testing with a magnet shows that the material is cast alloy, too.

The original had a stamped-steel clamshell construction that was welded together. Those seams of weld on the Legends M3 BB Grease Gun are beautifully-molded replicas of the original imperfections!



The M3 BB Grease Gun is covered by the regular, rather minimal, Legends 90-day warranty. However, as the valve is located in the detachable magazine (additional mags are available at $49.95), the main cause of possible problems with any CO2-powered gun can simply be resolved through swapping magazines.

A separate Allen (hex) wrench is required for installing CO2 cartridges. Of course, one is supplied with the gun. But if you loose it, you may like to know that the size is 6 mm metric.

Finally, you definitely will want to buy several additional magazines for the M3 BB Grease Gun! Given the huge fun factor, having multiple magazines pre-loaded with CO2s and BBs is the best way to ensure a long, enjoyable shooting session with this model.

In case of a jam, it may be useful to remove the “outer barrel” from the Grease Gun. This unscrews like the original, however the soda straw BB barrel is left inside.

M3 BB Grease Gun

Loading is aided by the BB follower slot cut into the magazine. However it’s necessary to be more careful than you might imagine when loading BBs.

By holding the magazine at a slight angle, it’s possible for the BBs to roll slowly down and stack in a “double column”. This is the only way to fit the full 60 BBs in the the magazine and you’ll probably find that feeding benefits from this effort, too.

The Umarex owner’s manual for the Grease Gun follows the company’s generally-excellent style. It’s well illustrated and includes English, French and Spanish language explanations.

SAFETY FIRST. As with all BB-firing airguns, it’s necessary to wear shooting glasses when firing this airgun. Also do not shoot at hard surfaces or water. BBs tend to bounce off these surfaces and may hit you, or something other than what you intended. If in doubt, don’t pull the trigger! Due to the realistic appearance of this product, handle it as you would a firearm. Do not display it in public or in any place where it could be mistaken for a cartridge firearm.



M3 BB Grease Gun

M3 BB Grease Gun

M3 BB Grease Gun

M3 BB Grease Gun

Legends M3 CO2 Grease Gun 0.177

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