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King Arms Full Metal M4A1 RIS Airsoft AEG Rifle w/ Advanced MOSFET

ID: 22714 (AEG-KA-AG-216-BK)
King Arms / Eagle Force859188227149KA-AG-216-BK22714
4.7 stars, based on 3 reviews
King Arms Full Metal M4A1 RIS Airsoft AEG Rifle w/ Advanced MOSFET
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Red Dot sight not included
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King Arms / Eagle Force


Canada Export CompliantCanadaExport Compliant
This gun has a muzzle velocity rating (FPS) between 366 and 500, and is compliant for export to Canada.
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Free shipping within lower 48 US states, no coupon code needed!


  • Full metal receiver and barrel assembly
  • Adjustable 6-position stock with rubber buttpad
  • Flip-up rear sight
  • Railed flat top receiver great for optics
  • Metal railed handguard with rail covers and vertical foregrip included
  • One piece metal hop up
  • In-line MOSFET, 8mm bearing gearbox with quick-change spring guide fully compatible with most Version 2 gearbox upgrades

Manufacturer: King Arms

FPS Range: 390-405


Length: 805mm - 890mm, Adjustable
Weight: 3120 grams
Inner Barrel: ~375mm
Magazine Capacity: 300rd Hi-Capacity. Works with Matrix, G&G, Tokyo Marui and other compatible M4 / M16 Series Airsoft AEG Magazines
Thread Direction: 14mm Negative
Gearbox: Ver 2 Full Metal, Fully Upgradeable
Motor: Long Type
Fire Modes: Semi/Full-Auto, Safety
Battery: 7.4v LiPo buffer type recommended (Battery not included. Wired to stock with a small tamiya connector)
Hopup: Yes, Adjustable
Package Includes: Gun, Magazine, Flip up sights, Manual

About King Arms / Eagle Force

King Arms was founded in 2004 with the mission to ensure optimum customer satisfaction by providing precision products and outstanding service. In 2015, we moved our headquarters from Hong Kong to Taiwan where we've continued to provide excellent products with the highest quality. While working with leading firearms manufactures, we provide to our customers a level of innovation and authenticity that can't be found anywhere else in the Airsoft industry. This goal is what continuously drives us to improve and gives us purpose.

3 Customer Reviews

(Write a review)

by Alexander D. on 05/13/2021
"I was skeptical to purchase this at first, since not many of King arms guns had reviews and this gun had a no reviews at the time. I used to airsoft when I was younger, So I bought this to get back in. Did not come with a battery, and finding what to buy was not easy, since evike and the actual manufactures website said different things. Kings Arms said it was a deans connection, and Evike said mini tamiya. I bought a mini Tamiya and a 7.4 Li-Po battery. Works great Ive gone Air-softing 6 times now from 10am-4pm on a single charge. My gun clocked 318 fps with .28g 6mm bbs. Had to adjust hop up since its originally tuned for .20g 6mm bbs. Feels great, except the handguard (the part of the gun with rail system) does not feel super tight. Took it apart and its just how the pieces connect. So when holding it the handguard rotates left and right slightly. So it just feels loose, but its not actually loose.
by Michael O. on 03/13/2021
"First I am super impressed with the rifle. The quality and construction is very hardy; it feels like a real M4 in size and weight. With that being said, its heavy. The weight is not for some people. In the test fire that I did; the rifle was spot on at 50 meters with iron sights. Awesome trigger response. I can hardly wait to use it on the field; right now none of them are open in my area. Still have a few more weeks to go until season opens up.
by Christopher J. on 04/16/2021
"--A Brief History--

About a decade ago, I was playing airsoft fairly regularly. Due to work, I had to stop playing. Recently had a change of location and I'm able to play again!

Why is that relevant to this review? Because the more things change, the more they stay the same.

A decade ago, airsoft M4's had a few common problems: Barrel Wobble, shoddy delta nuts, and lack luster accessories. The King Arms M4A1 RIS has these similar problems.

--A Matter of Perspective--

For $250, you get a full metal AEG with a MOSFET. In general, I'd argue the quality of the externals is pretty good. As with most airsoft guns, exterior finish quality falls short of the real deal, but in general, it's good enough to get the job done. Overall, the externals are on the mid to high end of what I'd expect for an airsoft gun.

--What's in the Box--

The gun, a hicap, the vertical grip, and two rail panels... ohh and some advertising papers. That's it... No unjamming rod, no manual, no speedloader... none of the things you've come to expect. The lack of a manual, online or otherwise is disconcerting. If you are a NEW player, be advised! The lack of a metal flash hider (unpainted or otherwise) is also disappointing...


So why the comment about the exterior quality in the history? Simple.... My gun's barrel came with a distinct wobble... like a plastic TM M4 receiver from the early 2000's wobble. So much so I felt obligated to tear my brand new gun apart because it's extremely annoying. This is where I found the first of "What the?" moments.

The Delta Ring Nut which holds the barrel on is a three piece affair. You have the part you pull on to remove the front hand guard, then the nut portion which actually holds the barrel on is two separate parts. The nut itself, is extremely thin, and as a result it actually deforms as the nut is tightened onto the receiver, which causes the barrel to loosen and wobble. Tightening this does NOT cause the barrel to tighten up so no amount of shimming the barrel will actually end the wobble. So that's a strong negative. That said, the outer barrel is a one piece unit, so if you solve the delta ring problem... so should the barrel wobble.

When reassembling, the actual delta ring spring broke... also not a good sign.

There are distinct mold lines on all of the plastic parts which I cut off with a knife. They were sharp enough to be a problem, hence the knife treatment. Overall though, the plastic parts feel like nylon, cut like nylon, and feel durable enough.

The crane stock is wired for a battery, but the WE 11.1V 4000mAh LiPo I bought does not fit. It's a big battery, so I'm not surprised. While I was inspecting everything, I went ahead and wired it for deans. The lead in the stock is fairly short, just long enough to put a battery in, but not much more. I suspect I'll be soldering in a short extension soon enough.

As for the rest of the externals, the front sight post is indexed by a set screw on the bottom of the barrel. The two cross pins which index the front sight on a real AR, sit in a groove which goes around the entire barrel assembly which means these two pins do little more than control the fore/aft movement of the sight. The set screw is a TINY set screw and thus has little control authority on the front sight so it moves. In general, a fairly poor design overall.

The flash hider is plastic, bright orange, and held in with a cross pin which has to be punched out to remove the flash hider. It's a standard negative 14mm flash hider so at least the common airsoft flash hiders work. The lack of an included one is... disappointing.

I have NOT had the gearbox apart. No point as the gun itself sounds GOOD for an out of the box AEG. The gearbox is smooth, no unnecessary whine or grind. The ROF with the 11.1V LiPo is... well... slower than expected at around 20 RPS. That said, it shoots a solid 390 FPS w/ .20's out of the box with an FPS variation of about /- 4 FPS. No complaints there, it's basically what you'd expect out of a factory tuned AEG.

The Hop Up Unit is the standard two gear affair held in place with a simple screw. It's no fuss, it works, just not overly well. I will have to update this after I actually field the gun, but Hop Up parts are cheap enough that replacing the hop up components is not out of the question. First game is in a few weeks, so I'll report back then.

I can't say I found the MOSFET... so I'm not sure if it's buried in the trigger unit like some of the more fancy units are? It's definitely NOT in the stock tube. The trigger assembly is a standard trigger, no microswitch here.

This AEG is a solid base for future building... I've already order a number of upgrade parts for the external short comings. So... overall, is it worth it? Sure. For $250 it's a solid deal with high quality gearbox internals. It has some problems with the externals and the accessories included with the gun. As my first King Arms AEG in over a decade, I can say I'm glad the issues are basically the same ole, same ole. Nothing awful, but some minor gripes I shouldn't be expecting out of an airsoft gun.

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