King Arms M203 long Grenade Launcher review

King Arms M203 Launcher and 40mm Grenade Review.


This item was supplied directly from King Arms, their communication is fantastic as always. I highly recommend them to anyone wanting to become a retailer.


The parcel was packed in an unmarked box which was very well sealed with tape. Inside the item was wrapped in bubble wrap and well padded with more bubble wrap. This item was not going to move and get damaged inside this box.


The item was sent via EMS recorded and took just under 3 business day to reach my door. It took 25 hours to get from HK to UK and then 1 day to clear customs and be dispatched to my delivery centre.

1st impressions:

My initial thoughts on the M203 and grenade were that they are both well made; the launcher has full colt trades on it with a serial number of 101389. The trades read “Colt’s INC Hartford Conn, USA. Launcher Grenade 40mm: M203 S/N: 101389, U.S.A”. What I like is that the trigger pin has a small cotter pin through it to stop it falling out like my Dboys one does.  The launcher is full metal except the hand guard which is a nice nylon fibre plastic. The release catch is a nice and smooth and the action is fairly stiff. I like how this one the barrel does not fall off when sliding forward as I have found with a few models I have seen. The launcher takes up to 180round grenades but will take the larger ones easily, its just getting them out takes a few seconds longer as you have to slide the grenade back into the tube and then pull it out rather than it just dropping out.

Testing the parts that are metal with a magnet you find the trigger guard, barrel mount and firing pin are steel (few the pins also steel)


Fitting the launcher to my M4 was slightly slower than the Dboys as this has a Screw fitment rather than the quick change feature of the Dboys. Once in place the M203 is secured in place nicely but as this version M203 was designed for King Arms/G+P M4’s which have a delta ring close to real steel dimensions and not the TM/Clone ones it can slide backwards and forwards and then is able to spin on the barrel. Fitment to a King arms M4/M16 does not have this movement. King Arms are also releasing a quick change 20mm RIS/RAS version.
Loading and firing:

Loading the grenade with gas took a few attempts to get the valve reset, I found unscrewing the base a few turns helped with the resetting of the firing valve. You then can load the bb’s and press them firmly down into the tubes, Tip upside down to remove any loose bb’s. Inserting the grenade into the launcher is easy; you slide the barrel down, slide in the grenade until its fully forward and then slam the tube shut. Select safe on the trigger until your ready to fire, The trigger has a 2 part safety where it will prevent accidental light knocks from setting the grenade off, Full on will not move even if the trigger is pulled with huge force. When you’re ready to fire you just aim, Arch the launcher upwards slightly to get a better range and spread and pull the trigger. Hopefully the grenade is not too full of gas to prevent the trigger from pushing in the valve. Once fired, slide the tube open and the empty shell will fall out. Pick it up or catch it and start again with the next shell.

On this model it was struggling to fire grenades on green gas. I advised King Arms and they checked the ones in their possession and they fired okay. I think I just got one with a slight problem (mine was a pre production model). The launcher how ever fired all my grenades with 134a and ultra gas in them.

This M203 Is one of the best made and looking launchers I have seen. The quality of the slide and locking mechanism is flawless.

The only down side is that it only fits a King Arms/G+P M4 series rifle. As they are also planning on 20mm version these should be a good attachment to choose for your rifle and if you have TM/clone system I’m sure with a small bit of modification to the fitting loop you can get these to fit fine.

As long as the firing of green gas is 100% corrected I would recommend these over any of the clones I have seen. Even over the Classic Army ones and such like. The Trade marks are fully licensed and perfectly engraved.


Construction: 8/10

Usability: 6/10 this is due to mine not firing the grenades on green gas. I would score 9/10 should the newer versions fire on green gas.

Value for money: 8/10

Ease of fitment: 8/10

Appearance: 9.5/10