ACTIONARMY AAP-01 Assassin JP ver. Review

This time, I'll be reviewing an Action Army AAP-01 Assassin, which is a custom-fitted item for a friend, so I feel like I'm a little late to the party.

As of September 2021, when this was written, this item is still incredibly popular despite being released last year, and there is very little stock left.

Looking at other people's reviews, I rarely see any problems or defects, but the product I received this time seems to have a clearly poor trajectory (out of the box). Unfortunately, I haven't been able to confirm it myself, but a friend who isn't particularly concerned about trajectory said so, so I thought there might be something wrong and took it in for inspection.

It seems the purchase was made around May 2021 at the very famous store ○Kei Paddock.

Now, let's get to the product review.

appearance

This is a side view of the entire structure.

Other side

The overall appearance is reminiscent of a modernized Luger MKII, which is a type I quite like.

Here's an update on the controls.

The design is such that all operations can be performed using just one index finger.

The slide stop lever and safety are ambidextrous. The magazine catch button appears to be reversible.

The grip is very well-designed, making it comfortable to hold and stylish.

The back looks quite similar to the Glock GEN4. It also appears to be compatible with various attachments (and apparently, some are already being sold).

Next, let's look at the back.

Next, let's look at the working bolt. The sights were orange at the front and green at the rear, a light-gathering sight? (They seemed to glow a little, but I might be wrong).

This bolt moves and extends to the back. The bolt stopper engages, maintaining this position.

Next is hop-up adjustment. Once the bolt is down, you can access it directly from the chamber. The adjustment dial was a little stiff.

On the back of the bolt you pull back is a lever to switch between semi-automatic and fully automatic fire. In the picture, the lever is tilted to the left, so if you tilt it to the right from the semi-automatic position, it will switch to fully automatic.

Next, let's look at the barrel. The tip of the barrel has a pre-machined M14 reverse thread, which is revealed when you remove the cap.

With the cap removed.

As will be explained in more detail in the disassembly and adjustment section, the inner barrel and hop-up chamber are fixed to the upper frame, so attaching any type of accessory will not affect its operation at all.

Finally, the trigger pull.

This is the cocked position.

The hammer is about to fall.

The stroke is quite long, and the hammer cocks just before the trigger is fully pulled. As I will explain later, this is an unavoidable design due to the inclusion of a full-auto function.

The overall resin material appears to be nylon-based. While it's relatively strong and flexible for a resin, it lacks rigidity and isn't suitable for sharp, precise shaping. Also, nylon has a high water absorption rate and can swell when wet, resulting in lower dimensional stability. However, under normal use, there shouldn't be any major problems.

Magazine

Let's take a look at the magazine.

Front of the magazine

Magazine back

Ammunition supply and gas supply routes

Magazine gas inlet

Because it's a JP specification, gas injection is easy.

While it looks very similar to Tokyo Marui's Glock magazine, the shape of the gas route packing in the gas supply route is different.

I've heard rumors that the Japanese version of the Assassin can use Tokyo Marui's Glock magazines, but I'll check later to see if that's true.

Live-fire performance verification

As usual, we'll check the actual firing performance.

Semi-automatic, original magazine

We will test the magazine by filling it with HFC-134a, with a surface temperature of 28°C and a room temperature of 23°C, loading 23 rounds.

Here's where the problem occurred. When I set the hop on the unit to 0 as usual, it only displayed a measurement error.

Thinking something was wrong, I tilted the gun downwards and the BBs started falling out. The reason was that with the hop-up set to 0, the hop-up protrusion wasn't descending sufficiently and wasn't holding the BBs properly (they were falling out). I checked by putting BBs into the chamber and pushing them with a stick, and found that they could only be held properly with the hop-up set to maximum.

The lack of BB retention in this hop-up is what the owner mentioned about the poor trajectory (the BBs aren't coming out at a proper muzzle velocity).

Let's try again, this time with G&G 0.2g bio BBs and the hop-up fully engaged.

The initial velocity is quite high.

The cause is likely that the gas discharge pressure to the barrel is too high, and the BB is not held in place by an insufficient hop-up protrusion, causing it to fly off before sufficient pressure is applied to it. As a result, the appropriate hop-up rotation and muzzle velocity are not being achieved. This issue will be addressed in the adjustment section.

If you're interested, please also check out my review of the chronograph.

Semi-automatic operation video

ACTION ARMY AAP-01 Assassin Semi

Incidentally, because the bolt in operation is light, you barely feel any resistance from the recoil.

Fuel efficiency

Next is fuel efficiency.

This is the weight of a completely empty, original magazine.

Fill this to the brim with gas.

This puts in 15.5g of gas. That's a normal amount for a handgun.

This is the weight of the magazine after firing 23 rounds in a row.

It seems to have consumed about 9g, which works out to about 0.4g per shot. The fuel efficiency isn't as good as I expected. For reference, the Tokyo Marui Glock 17 Gen4 uses about 0.33g, and the UMAREX/VFC gas blowback uses about 0.3g.

Watching it in operation, I noticed a gas leak, so I suspect it's either an airtightness issue or poor fuel efficiency due to the timing of the gas cut-off. A simple calculation suggests it can fire about two magazines (depending on conditions).

Flute, original magazine

Next, since it has a fully automatic function, I tried testing it under the same conditions.

The magazine cooled down too quickly, causing a significant drop in muzzle velocity. If you want stable performance, I strongly recommend using a long magazine with a larger gas and heat capacity.

The gas supply was so poor that it ran out after firing about one magazine. When I observed its operation, the bolt's movement speed was too short and fast, so it seemed like gas was being released almost continuously, which was understandable.

Full operation video

ACTION ARMY AAP-01 Assassin Full Auto

Because of the fast rate of fire and short gas cut-off time, gas is constantly being released, causing the magazine to cool down quickly.

Can Tokyo Marui's Glock magazines be used interchangeably?

Next, we'll check if the magazines from Tokyo Marui's Glock can be used as a replacement.

The magazine's condition will be checked at point 23 with a full HFC-134a tank, a surface temperature of 28.6°C, and an ambient temperature of 23°C.

The BBs used are G&G 0.2g, and the hop-up setting is at maximum.

It is possible to fire the shot, but the initial velocity is extremely high.

However, it does not function properly. A bolt failure occurred.

In this state, the gun cannot be fired; it requires manually forcibly closing the bolt. From my experience, this occurred about 30% of the time.

The cause is that the height dimension of the gas route packing in the Tokyo Marui Glock magazine is different.

In conclusion, while it's not impossible to fire a Glock using Tokyo Marui's magazines, it's not perfectly compatible as bolt closure problems can occur.

Also, when I tried to buy the overseas version of the Assassin at a certain shop, they told me that the overseas version has a gas inlet for high-pressure gas, and that if I wanted to use Tokyo Marui's Glock magazine, I would need to change to a dedicated gas route packing to make it usable.

This issue applies not only to the overseas version but also to the JP version, so those considering using Tokyo Marui's Glock magazines should be aware of this (the gas injection valve has been modified for domestic use).

G&G Bio-Bullets 0.2g
It's inexpensive and accurate, so I use it for a wide range of purposes, from performance testing to airsoft games. It's been my favorite since it first came to Japan (around 2008). It lasts a long time for a biodegradable product.

G&G Bio-Bullets 0.25g
It's 0.25g. I generally use 0.25g BBs when playing airsoft.

Summary and customization options

While it's made with reasonably good quality, it's still difficult to say whether it's as usable right out of the box as a domestically produced product.

It might be due to individual differences, but the balance between hop-up retention and propellant gas volume is off (causing BBs to fall out and poor trajectory).

As is typical with overseas products, there is very little grease applied, so greasing is essential.

Since the fuel efficiency isn't very good, I'd like to consider measures to improve airtightness.

In terms of customization direction

will be important.

I'd heard rumors that it was pretty good right out of the box, but unfortunately, this particular unit is a bit disappointing. However, its simple structure makes it easy to customize, so I think it's a pretty interesting product as a base.

Next time, I'll show you how to disassemble it.

・ACTION ARMY AAP-01 Assassin Black
This looks like a really interesting base for exterior and internal customization. Surprisingly, they had it in stock at a reasonable price. By the way, the only difference between the overseas version and the Japanese version is the gas injection valve on the magazine.

・ACTION ARMY AAP-01 Assassin DE
I personally like this color.

·magazine
This test revealed that Tokyo Marui's Glock magazines cannot be used as is, so it's probably safer to just buy the genuine article.