Pocket Pistols - Marushin Derringer and COP .357

Derringers (or deringers, if you prefer) are odd things.

Despite their association with Mr Derringer, multi-barrel pocket pistols firing one shot per barrel have been around for a long time.

Traditional Derringer styling

It is not surprising, therefore, that someone chose to replicate them in airsoft form and, although others have existed in the past, the current 'someone' is the Japanese Marushin company, known for their NBB output, which means the Derringers fit right in.

The COP .357 was designed as a Police Officer's concealed backup gun

What I have reviewed here is the 6mm Derringer model, now replaced by a strictly two-shot 8mm version, and a black COP .357 with standard barrel length.

In real steel these represent the earliest and latest Derringer-style guns, with the two-shooter being a contemporary of the Colt SAA and the COP a 1970s product.

In the Box

The Derringer box is very basic, much like the gun. The lid is blue with a picture of the Derringer and the base of the box is a polystyrene bed into which the gun and, presumably (my gun was used), some BBs rest.

Just the Derringer!

The newer COP, by contrast, comes in a colourful box and the box base is made up of cardboard with the COP nestling in layers of corrugated cardboard, cut out to hold the gun.

Bright box, but not even some BBs with COP!

First Impressions

The Derringer is tiny and actually looks a bit cheap and nasty with some very prominent seams and virtually no moving parts.

Aside from the ugly seams, the silver finish is actually pretty good and there is a metal hammer and trigger (little more than a stub, as befitting a Derringer)and separate black grips.

Silver finish is good, but only metal parts are hammer and trigger.

You will notice, if you look down the muzzles, that the bottom has a 6mm inner barrel, but the top one is blocked.

The COP is very solidly made. It is quite a bit bigger than the Derringer, but it feels remarkably solid for what is still a small gun and a large part of the frame is made of metal.

COP looks and feels solid and well made.

Unlike the 6mm Derringer (although the 8mm is much more like half a COP in this respect), the COP breaks open, like the real thing, to allow you to load 4 of the big 8mm BBs.

The COP also features a metal trigger and safety.

Interestingly, despite their tiny size and short range raison d'etre, these two guns both feature Hop-up (SSB - Super Sonic Barrels - in Marushin's terminology).

Closer Look

Marushin Derringer 6mm

Top barrel blocked off - serves as magazine. Note seam down barrel!

The Derringer's blocked upper barrel is its most interesting point. You will see that there is a black plug in there, which turns a quarter turn and allows you to withdraw a spring loaded plastic rod.

8 BBs go in the top barrel.

This is actually a small magazine type system which allows you to load 8 6mm BBs into the upper barrel. These are then fired, each time the Derringer is cocked and fired.

Hammer must be cocked back, by hand, for each shot.

You need to cock the Derringer, like a springer, between each shot. This is realistic to the real thing and the hammer and trigger actions are both impressively smooth. However, I have not found a way to successfully cock the hammer and keep the Derringer on target, which has a detrimental effect on the accuracy that can be achieved.

Gas fill valve on butt. Seam is VERY prominent.

Gas is loaded into the butt of the Derringer pretty much where you would expect and poses no special problems.

Simple sights.

The sights are crude and basic, but do provide a rudimentary aiming system.

The body has a barrel release catch (and what looks like a safety) moulded in, but is all a two piece casting, crudely joined down the middle with a prominent seam. These sort of things bother some people more than others, but I find them annoying, although I cannot say if the newer 8mm Derringer suffers in the same way.

There are no markings, at all, on the Derringer, except for a small ASGK marking on the right side, between the barrels.

Marushin COP .357 8mm

In comparison with the Derringer, the COP .357 is a beautifully made gun. In fact, after seeing the Derringer, I expected the COP to be similarly poorly finished off, but in black, at least, it stands comparison with KSC or Maruzen guns, with none of the ugly seams and a major part of the frame being made of metal.

Working safety catch.

The 4 barrel system is quite different to the Derringer. Pulling back the rear sight (made of metal), releases the barrel assembly which springs open to reveal 4 separate 8mm, fixed Hop-Up equipped, barrels. The 8mm BBs simply push into each chamber and you swing the barrels back up unit they lock into place.

Barrels hinge to allow loading of 8mm BBs.

Gas, as with the Derringer, is loaded via a fill valve on the base of the butt and the COP 357 has a clever mechanism with turns the gas release valve between each barrel in turn, which reflects the real steel design quite accuractely, in concept, at least.
The downside to this, compared with the Derringer, is a much heavier trigger pull as the mechanism is advanced by the first part of the trigger pull.

The business end - Red dot indicates next barrel to be fired.

The trigger itself is an all metal blade and, as well as the rear sight, there is a small safety catch on the right side grip, which is made of metal. The plastic grips are separate units, too. The foresight is a simple, unmarked, post.

Butt fitted fill valve - Rear of frame is all metal.

The COP .357 markings look pretty accurate to the real thing (from pictures) with a COP logo and "COP INC. TORRANCE, C.A. U.S.A." on the left rear of the frame and "CAL .38/.357 MAGNUM" on the barrel assembly's left side. The right side is marked "MARUSHIN INDUSTRY CO,LTD"/"MADE IN JAPAN ASGK"

Shooting Impressions

Long range accuracy is not the avowed intent for such weapons, being intended, in the harsh real world, to be used at very close quarters.

However, I subjected both guns to my usual 5m test and achieved some interesting results, with both suffering inherent flaws in their design in terms of accuracy achievable.

Click on image for bigger version in separate window.

The guns were also tested for trigger pull weight and velocity.

Marushin Derringer 6mm

Over 6 shots, at 5m, shooting off-hand, my Derringer placed its best 5 rounds in a 13 CM (5.5 inch) grouping. This is the worst, measurable, accuracy I have ever achieved, but the depressing raw figures do not, in this case, present the whole story.

The Derringer needs to be cocked, by pulling back the hammer between each shot, which causes the whole gun to be taken off-target each time. 4 rounds were in a reasonably fair 7.5CM (inches) and, with some care and more practice, it is safe to assume a best 5 grouping could be achieved in the same sort of diameter.

Power wise, as you would probably expect of such a small gun with very short barrels, the Derringer is nothing special.

With Abbey Ultra gas, at 16C, with .2g BBs, the Derringer averaged just 145 fps over shots. Experience suggests this would relate to around 156fps at 20C.

Shot      FPS
1 133.6
2 130.3
3 132.3
4 152.9
5 156.8
6 154.5
7 152.1
8 150.8

As you have to cock the Derringer for each shot and there is no cycling of the mechanism to chamber a BB, the trigger is actually lightweight at just 770g.

Marushin COP .357 8mm

Over 6 shots, again at 5m shooting off-hand, the COP .357 produced a best 5 grouping of 9.5CM (3.75 inches). Again, like the Derringer, this is at the poor end of all my testing, but is not a full picture of the gun's potential accuracy.

The issue with the COP .357 is the long and heavy trigger pull, necessitated by the gun's unique rotating mechanism. The long pull, and a sudden actuation of the firing mechanism, once the gas valve is aligned to the new barrel, makes it very difficult to keep the gun on target as you pull the trigger. The best 4 shots were in a 7.5 CM(3 inch) group with the other 2 shots falling far to the left and right of the aim point.

Once again, care and more experience with the gun could, almost certainly, yield 5 shot 7.5 CM groupings.

With large .34g BBs, the COP threatened to offer very poor performance, but the gas system is obviously a lot more efficient than the Derringer.

With Ultra gas, .34g 8mm BBs at 20C, the COP .357 managed a fairly respectable 195fps, equivalent to 253 fps with .2g BBs.

Shot      FPS
1 197.3
2 199.3
3 169.8
4 179.5
5 200.2
6 169.6
7 178.3
8 242.4
9 248.9
10 166.4

As I mentioned, the trigger pull is very heavy and long. It requires a 2,500g+ pull, although this doesn't compare directly with other tests as the gun is strictly double action.


The Derringer can only really be considered as a novelty or last-ditch backup gun. The seam lines are disappointing, giving the gun a rather cheap look, which doesn't reflect the actual quality overall.

Unless the 8mm version features much less prominent seams and a more efficient gas system, you would need to really want a Derringer for me to recommend one.

Fun, but not the most practical of airsoft pistols.

The COP, however, is more practical, although with just 4 shots and only average power, it's unlikely to make a very practical skirmish sidearm.

It is, however, solid and nicely made and will attract attention wherever you go - Surely enough to recommend itself!

Marushin Derringer 6mm

Weight : 160g

Realism : ***
Quality : ***
Power : **
Accuracy : **

Marushin COP .357 8mm

Weight : 400g

Realism : ****
Quality : ****
Power : ***
Accuracy : **

Link to info on real steel COP .357

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