Vanaras 40mm POM M203 Grenade

Vanaras was kind enough to send a sample of these to me via the guys at RSOV.  Since word of these hit the market I’ve been itching to get my hands on one.  Vanaras has thrown convention out the window and decided to build a low cost M203 grenade shell by changing up the materials they used.  At 133 grams, you get a shell that’s about 29% lighter than the equivalent metal shell; and at $11.99 it’s a steal.  Do you get what you pay for or do you get a lot more?

First Impressions
The first thing I thought of when I got one of these in my hands was,”Wow”.  Why? Well, they feel like they weigh nothing.  I normally carry 4-5 grenade shells on me at a time when skirmishing, and a little weight reduction would be nice.  The machining of the plastic also looks top notch with no burrs or errant edges along the “barrel” openings. The reset spring also felt nice and stiff.  The instruction sheet that came with it was also written well (in comparison to most “engrish” airsoft manuals out there).

Materials and Construction
What is POM you ask?  POM is acetal polyoxymethylene resin, marketed by DuPont it’s known as Delrin.  According to DuPont:

Delrin® bridges the gap between metals and ordinary plastics with a unique combination of creep resistance, strength, stiffness, hardness, dimensional stability, toughness, fatigue resistance, solvent and fuel resistance, abrasion resistance, low wear and low friction.

What we have here is a resin that can be molded to make parts that can be used to interface with or replace metal components where areas of weight or cost are an issue.  The benefits of POM are its hardness and strength as well as fatigue resistance.  Those make this an advantageous choice for a reduced weight and cost M203 Airsoft grenade shell.

The fill valve is a typical design consisting of a metal valve with rubber seals.  It is nice to see that they put a rubber gasket in the top of the fill valve so you don’t spew propane everywhere while you’re filling it.  I noticed that the dimensions of the top of the fill valve are close to those of the Madbull valves.  I will have to test this to see if they are compatible.

The o-ring that is used to retain the bbs seems to be pretty thick and flexible, and is placed in a deep grove that should keep it from popping out when firing (unlike some of the King Arms shells).

The other end of the grenade brings us to the trigger mechanism and the exhaust valve.  The mechanism is all metal with a rubber o-ring.  Against the manufacturer’s warning in the manual, I took the unit apart.  Inside it’s put together much like every other Airsoft m203 shell.  There is 4 ball bearings (similar to the Madbull design), that are 4mm each; these are seated in a metal valve with a rubber o-ring on it.  Below that assembly is the spring and push button.  I noticed that the push button had some indentations on it created by the pressure of the bearings (click thumbnail below).  That is not promising, as that means that the bearings are wearing away at the part of the push button that functions like a sear.  If it wears away too much, then it could cause the grenade to no longer hold gas at pressure.  This assembly is firmly seated in a metal ring which resides in the bottom half of the shell.  This ring locks the valve and trigger mechanism into the bottom half.

When disassembling the grenade, I noticed that the ball bearings did not fall free from the valve assembly.  I tried to push them out, but they stuck in there good.  Now is that because they were somehow “crimped” in or are the tolerances that far off and they were “shoved” into place?  I honestly don’t know, but they do seem to move easily back and forth as they should.  I guess it could be seen as a feature that the bearings don’t fall out and roll away to never be seen again.

The threads that hold the upper to the lower are nice and cleanly cut. The fact that they are Delrin (POM), make them glide easily when screwing together.

Okay, it’s an m203 shell so there’s not much to say in the way of features.  It can run on Green Gas (or propane for you real men out there), and it holds 48 rounds of 6mm bbs.

First let me say that the temperatures here have dropped significantly over the past few days with the high temperatures just reaching 63ºF.  That’s pretty low for testing gas m203 shells, so I warmed up the shell to about 80ºF before firing to improve consistency and give reliable results.

Using a metal rod I pushed the valve back into place.  After filling the shell with propane I measured it and calculated that this shell holds 1g of gas.  That’s a bit on the light side from what I’ve seen, but this shell does have a lower capacity of bbs than my other shells.  Filling the shell with bbs I gave it a good shake.  No bbs fell out.  That’s promising.  I find it quite aggravating when I pull out a grenade shell and find half the bbs down in my pouch instead of in the shell.

With a firm push of the plunger and a loud report indicative of an m203 gas shell grenade going off, 48 bbs went down range.  All test shots were done with the shell parallel to the ground with little to no wind.  At full capacity (48 bbs), and a full fill of gas @ 80°F, the average distance for the furthest bb was about 80 feet and the closest bb to hit the ground was about 60 feet.  The spread had an average width of approximately 17.5 feet.

I then tried filling the shell with it at room temperature (about 72°F), and then letting it sit outside at 59°F for 10 minutes.  I then fired it off, and to my surprise, there was very little if any loss in range or apparent velocity.  I expected that the reduction in temperature would reduce the pressure of the gas resulting in decreased range, but that turned out not to be the case.  This is a real benefit of using the POM material as it works as a great insulator, thus possibly making for a good shell for winter use.

I then repeated the first test, but this time with the m203 shell with only 4 bbs in each chamber instead of 8.  The range overall increased by almost 20 feet, but the grouping was much looser.  Personally I feel this is a good compromise, and I think the gas:load ratio should have been closer to 1g:24bbs and that 1g:48bbs was asking too much.

I did find that resetting the grenade was a bit troublesome.  I’m no newbie when it comes to these things, but man did I have a hard time resetting these till I found the problem.  Typically you just push the valve all the way in and if necessary give the base a twist or two to drop the sear back into place.  I did that over and over, and the sear would not drop all the way back.  I’d try to fill it and get a lot gas venting out in a sporadic manner (like a drawn out fart… really).  I took apart the shell a number of times before I realized that the metal ring that holds the valve and trigger assembly in place (see picture below) had crept up towards the top of the shell by a few millimeters.  Pressing it down into place solved the problem.  I found that as long as the shell was warm, this wasn’t a problem, but if the shell was cold (due to low ambient temperatures and cold propane hitting it), that the ring would creep up.  I think the problem lies in the metal chosen.  I’m guessing it is aluminum by appearance (I have no scientific basis for that assumption), but it might be contracting allowing it to move up when resetting the valve.  My suggestion to Vanaras is to put a tighter fitting ring in there, or perhaps to put a notch in the outside of the ring and put an o-ring on it before sliding it into place, that would help hold it in the correct position.

I also tested filling the shell with the Madbull valve installed as opposed to the stock Vanaras valve.  While the threads and overall length of the Madbull valve is shorter, it still fits and functions flawlessly.  This is nice since you can easily find Madbull fill valves here in the USA in case you were in need of a replacment.

When it comes to innovation in airsoft, this has to be one of the more innovative products I’ve seen as of late.  With a reduction in weight and a significant reduction in cost, these are what many Airsoft players have been dreaming of.  While the range performance isn’t anything to write home about, the spread is great for a 48 round shell; not too wide and not too narrow.  I’d like to see them remake the shell with a bit more capacity for the gas if possible.  One thing to remember is that I did all my testing by firing the shell parallell to the ground.  In the field you can of course angle it upward and get dramatically more range out of it.

As someone who plays Airsoft at an outdoor field mostly, I can say that reducing the weight of my rig by switching to these shells might be nice.  The ability to fill them with gas and not worry about the bbs falling out into my pouches or the gas pressure dropping with the ambient air temp dropping, sells me on them.  If you’re a CQB / indoor player, I think you’ll find that the fps and spread are just what you need for hallway control and room clearing.  Overall I say that Vanaras has brought innovation back to airsoft, and while this first run does have some drawbacks, at $11.99 through RSOV, you just can’t say no!

The Numbers:

Construction: 7/10 Great machine work on the POM material.  Everything is smooth and the bbs move easily in the barrels.  I would like to have seen some better machining of the metal valve internals though.

Durability: 9/10 The POM material is down right tough.  The only concern I have is the plunger / trigger /sear as the bearings are marking the surface and could cause it to prematurely die… but at $11.99 you probably would have gotten your money worth out of it anyway by that point.

Performance: 7/10 I would like to have seen the valve mechanism reset easier, as well as a bit more range  overall.  Bang for the buck though… these can’t be beat.

Vanaras has updated thier design to overcome the problems noted in this review. I have an updated version on the way and I will make sure to let you all know of the quality and performance changes. In addition I must say that this shell performed admirably the other day in weather that was in the low 40’s Fahrenheit. It wasn’t as amazing as I’m sure it’d preform in 80+ weather, but it did out perform all my other shells easily.


I recieved the updated design.  I must say that it’s a marked improvement on an already innovative product.  The spring on the push button seems stiffer, and the overall machining is much better.  The tolerances seem much tighter too.  The valve is machined and what appears to be chrome or nickle plated.  The plating is decent, but is flaking a bit.  The bearings are able move much more freely.  The retaining ring at the bottom of the shell is now held properly in place and does not move.  This prevents the problem with filling that it exhibited before.

New ratings:

Construction: 8/10 Better tolerances and better machining increased this rating.

Durability: 9/10

Performance: 8/10 An improvement to the overall design results in easier use, thus a higher rating.  The overall range and spread is unchanged.  This rating has been increased accordingly.



One response

9 12 2008
UPDATED: Vanaras 40mm POM M203 Grenade « The Festering Wound of the Airsoft World

[…] Links: Vanaras 40mm POM M203 Grenade Review […]

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