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Beretta M12S - MGC

This is a true classic in the airsoft world.

Compact SMG is very early example of Airsoft Gas guns.

Manufactured by the Model Gun Company of Japan in the early eighties, the Beretta M12S Penetrator was one of the very first airsoft guns to actually replicate a real gun AND to fire full auto.

Extended stock and hi-cap magazine.

In the Box

My M12S didn't come with a box (or the usual collection of accessories), but I received this image of a boxed version from the person I bought mine from.

What you got new - Note shorter magazine compared to mine.

As you can see, you would normally get the gun, one magazine, a loading tube and rod and the gas rig, consisting of a 'power booster' expansion can and pipes and connectors to connect to a gas can (with a thread under the nozzle, not easy to find these days) and to the push fit connector on the rear of the receiver.

The gun also (in standard form) comes with a complicated attachment to hang the gas cans on the end of the barrel.

First Impressions

Opening up the box with the M12 in, my first impressions were pretty good.

Markings are well defined and accurately reflect the real gun.

The gun is very solid feeling and the metal stock is very sturdy, despite looking a bit flimsy.

My magazine is extended 50 round version.

The gun is quite nicely marked, but the finish is a bit glossy, lending a slightly toy like feel. This effect, however, is far from uncommon on older gas guns, and this must be nearly 20 years old and the gun seems (and presumably is, having lasted this long) very solidly made.

Personally, I think it looks more realistic than 90% of AEGs I've seen, so the 'toy-like' reputation seems undeserved.

Selector switch, Safe (S), Semi (I) and Full (R) Auto.

The magazine is particularly fragile looking, bearing an uncanny likeness to the MP40 springer mag! However, it seems to do the job well enough. Not sure how well it would stand up to someone falling on it, though!

Closer Look

Starting at the back of the gun, the rear cap is removable, and there is sling mount, secured by the gas valve. The rear pistol grip has the trademark, grip safety (when I first saw this I assumed it was a nasty airsoft add on, but sure enough the real thing has it!).

Stock is full metal and quite sturdy. Note Gas valve on rear of end cap.

The stock is solid bar iron (slightly rusted to prove it), making it very strong and it locks into open and closed position with a reassuring click.

Cocking handle is fixed.

Unfortunately, the cocking handle is totally fixed, meaning you can't rack it, even for show (I found a Cap firing version of the M12S on the internet, complete with a blowback system, where the handle flies back and forth on each shot, as the shells eject).

The selector is set for Safe, Semi Auto and Full Auto operation, by means of a switch on the left of the receiver, just above the trigger.

Rear sight offers varying size apertures for more precision

The sights are pretty good, with the rear sights replicating the flip over style set for 100 and 200m, whilst the front sight is an odd locking metal post.

Front sight is odd metal post.

The gun is quite nicely marked, with the Beretta markings raised along the receiver. These read 'P.M.BERETTA MOD.12S-Cal.9mm Parabellum K040208 - 84' on the left hand side.

The right hand side of the frame (Above the trigger) is marked with the MGC logo with "MODEL GUNS CORPORATION", "MADE IN JAPAN" and the ASGK mark.

Butt of stock folds up when stowed.

I couldn't resist the temptation to paint the selector markings, red for I and R and white for S, to accurately reflect the real weapon.

The foregrip is, like the rear, fitted with gloss plastic grips, like the real thing and the butt of the stock folds up above it, along the side of the receiver, when folded.

Gas system

Actually getting the M12S to operate proved something of a challenge.

First off, most modern 134a gas doesn't have a thread on the top of the can, under the nozzle.

The person I bought it from was very helpful and pointed me in the direction of HFC Super Power Green Gas (which is actually 134a, not HFC22, which is more commonly referred to as Green gas in the UK), which has a thread. I obtained some and it DID fit the attachment and it did (once I shortened the nozzle by about 3mm) feed gas into the expansion can and operated the gun.

However, the gas wasn't easy to find and quite expensive to ship to me, so I decided to explore alternatives and decided (after checking with the Classic Airsoft forum members) to try Airbrush propellant. This is widely and cheaply available in the UK.

I purchased a can adaptor with a 1/8" output from The Airbrush & Spray Centre.

Push fit gas connector.

I then found Robot Store UK , who sell lots of pneumatic parts for those 'Robot Wars' type robots - They provided a 1/8" - 6mm push fit adaptor and 10m of nylon hose (only needed about 2 inches! :^) ).

It all fitted together fine and firing the gun with airbrush propellant seems, if anything, even more powerful than with the HFC gas.

Airbrush propellant setup (one way valve not shown) - Expansion (POWER BOOSTER) tank increases power.

I then ordered a one way valve, from robot store, which lets me shut off the gas supply from the propellant can without dumping the contents of the booster can.

Airbrush propellant comes in 750ml cans and is a fair bit cheaper (in the UK anyway) than 134a, although I'll need to spray the gun with silicon oil more frequently as it has no lubricating additives.

Shooting Impressions

Carrying out my standard 5m/6 round, off hand test, without the stock, I produced a spread of 6 inches (15CM) in semi auto (marked with circles on the target).

However, this was misleading as a guide to the gun's ultimate accuracy. The reason for this is that, even a 20C, the gun produces a poor velocity with simple airbrush propellant. Due to this the first rounds fell short (the two at the bottom) and I put a third too high.

Once I adjust the aim point, to allow for the drop off, I put the remaining 3 rounds in a 1.5 inch (4 CM) group on the edge of the centre area of the target.

Click on image for bigger version in separate window.

Full auto, 7 rounds all hit the target with 5 in the target centre and within 2.5 inches (5.7 CM) of each other. The remaining two shots went low as the airbrush propellant seemed to freeze the system again.

Testing a burst, back in my loft (around 25C) the power was much more impressive and there was none of the cool-down seen during the testing.

I've come to the conclusion, that, whilst the gun will work on airbrush propellant, it really needs more temperature than we get in the UK to be efficient, so I think I need to get a CO2 setup to make this work effectively. However, a proper classic airsoft/paintball system will be expensive and so I MAY try one of those KWC CO2 powerlet adaptor rigs next.


I obtained a KWC CO2 adaptor (and also experimented with a Butane/Propane mix, briefly) and chrono'd the M12S with all 3 gas sources, at a chilly 16C, using Excel .2g BBs, although constant freeze-ups (with the Airbrush and Butane/Propane) and running out of gas (with the CO2), limited it to under 5 shots with each.

Gas Source Average fps
Airbrush Propellant 118
Butane/Propane Mix 131
CO2 244

The CO2 adaptor certainly produced more usable power (and reliable performance, I had no freeze-ups with it), but the capsules only last 1-2 magazines before running out of gas and needing replacing. I shall revisit this when the weather warms up.


Overall, the M12S is an interesting piece of airsoft history and fun to shoot.

MGC markings visible ahead of trigger. Note pistol grip safety, which is replicated from the real gun and works.

Nicely made, it shows its age in the fragile looking magazine and rather shiney finish.

The full auto sound is quite impressive, despite the lack of any blowback mechanism and the rate of fire seems (subjectively) impressively high, too.

The need for external gas supplies makes it fairly obvious, to me, why AEGs now dominate the skirmishing market, but as a piece of airsoft history, this big SMG is an interesting and fun piece.

Weight : 1,800g

Realism : ***
Quality : ***
Power : Depends upon power source - Too weak for the UK on airbrush propellant, average on CO2 adaptor.
Accuracy : ***/*** Full Auto

Real Steel link at World Guns

An excellent webpage relating to the Beretta M12S

Model Guns - Supplier of my MGC M12S.

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