Background Information
The WE M4 is definitely a unique piece of kit. As one of the cheapest GBB rifles on the market today, it is relatively cheap to get into the GBBR scene with something that will last enough. There is a large number of replacement parts and a few upgrades laying around in retailers bins. One of the more important things to take away from this is how close the rifle actually is to the real deal. I will not mention too many specifics, but the way the mechanism is designed does not allow it to fire real rounds.
Since the quality of WE-Tech can be 'questionable' at times and the dimensions are close to that of the real steel, some of the parts can be replaced to increase the durability. A common one is the charging handle. The stock OEM (Original Equipment Manufacturer) part is a cast metal, most agree to be 'pot metal', which is not a strong way to manufacture a part that basically has to put up with being smacked around. The design is also bad because it puts a lot of force on the tip of an 'L' shaped piece, which puts a bending force on it. To make a long story short and cut out all of the engineering junk, the front section of the charging handle will break off in due time.
The cost for a new replacement part is $15, which just so happens to be around the same price for a real, extruded charging handle. If you have all the tools laying around, the only additional cost for this mod is $0.50 for some tension pins, easily making it worth it. Real steel charging handles are made to withstand much greater forces, and for much longer. Even though I used an extruded charging handle, the mod is the same for forged handles (usually these are slightly more expensive).
Tools Required
This mod didn't require a full machine shop, but some tools will make it a lot easier. This is what I used:
- Hammer
- Drill Punch
- Cordless Drill
- 1/16 inch drill bit (titanium nitride coated)
- 3/32 inch drill bit (titanium nitride coated)
- 1/8 inch drill bit (titanium nitride coated)
- 1/8 inch diameter x 1/2 in tension pins
- Digital Caliper
- Stock WE Charging Handle
- Table Vise (and some wood to pad it)
You don't HAVE to have caliper, OEM charging handle, or the 3/32nd drill bit, but I have my reasons. The caliper was used to get relatively close dimensions by comparing measurements, the 3/32nd drill bit was just another step for boring out the hole (more on that later), and the stock handle was for comparison purposes. Everything else I feel is required. You could even go one step further and use a drill press and a level for a perfectly vertical pin, but I think you can do pretty well with just a padded vise and a cordless drill.
The Modification
This is a very simple mod to do, but for those who haven't done something like this before, that is who I directed this guide towards. If it seems like I drag on, you can skip to the titles of the sections.
1. Measurement of the OEM part
Using the digital caliper, compare the heights of the two 'L' shapes on the charging handles. You will find the OEM part is a tad bit longer. This is the only part you need to modify on the real one. You can test this by putting the RS (real steel) one in your WE M4 upper receiver. If it does not slide smoothly, then additional modification will be needed, but I have tested with 3 different upper receivers (all different versions) and found all three charging handles to run smoothly. Please note that while my caliper is able to measure 4 decimal places, I rounded to 3 since it is really all you need to worry about. This isn't going on the space shuttle for a trip to Mars.
Stock OEM part - 0.642 in
RS Extruded Charging Handle - 0.589 in
As you can see, there is a 0.053 inch gap to make up. If you don't make up this difference, the charging handle can run into a plastic part of the carrier that was not designed to handle the stress. You will see it on the Open Bolt WE M4's. It is just a small plastic square piece that is bolted on to keep the loading nozzle in the carrier.
2. Put the RS charging handle in a vise
This is pretty self exclamatory. The part you want to drill into is the lower piece of the 'L' shape, so this should be facing up. You can notice from my set up in later pictures that I supported the charging in the vise with some small pieces of wood. This helps prevent bending of the handle when you hit it with a hammer. Wood is soften than aluminum, so the stress will be absorbed into it instead of your charging handle. You want to tighten the vise so that way it does not move, but not so much that is warps or bends. The wood also provides spacing the help with this, but the vise should be snug not tight. Make sure you do not clamp the small parts sticking out from the sides of the charging handle. Those are the guides that run along the inside of the upper receiver to keep the handle in place. If you clamp that area too tightly, you will deform the handle, resulting in binding of the carrier. Just make sure you leave that part out of the vise when you tighten it. If you are unsure of how to set it up, look at the various pictures I have posted here and you will get the idea.
3. Mark the hole for drilling.
This I feel is a very important part, and why I used a drill punch. For those inexperienced in machining and metal work, a drill punch is used to help guide a drill bit into metal. Drill bits, especially when used in a cordless drill, have a tendency to 'walk' on the material. This means you could line it up perfectly in the place you want a hole drilled, but the bit could drift to a different spot and begin the hole in a not so ideal place. A drill punch solves this problem by marking a small indentation in the metal, right in the location you want. Simply position the punch in the spot you want and hit it ONCE with a hammer. The charging handles are made of aluminum, which is a soft material compared to the drill punch. This means the dent is easy to make with a simple swing. You can hit it more than once as long as it is in the same location. You can tell when you have successfully punched the handle when you can run your finger over it and feel the indent.
4. Drill a 1/16th inch diameter hole
Again, this is pretty self exclamatory. I used 1/8th inch tension pins for this, so why would you drill a hold smaller than the one you need? There is a simple answer for this, the smaller hole is called a pilot hole for guiding the larger one. Even though a drill punch was used to mark the spot, the 1/8th inch bit can still walk or drift. If you drill a smaller hole first, then it is easier to have the larger bit drill the right sized hole in the spot you want to. Aluminum is a soft material, so it doesn't take much to cut into it.
5. Drill a 3/32nd inch diameter hole
This is just an intermediate hole. I wasn't sure if the 1/16th hole would be big enough for the 1/8th to drill properly, so I used the 3/32nd to help bridge the gap. I do not know if this was unnecessary or not, but I played it on the safe side.
6. Drill a 1/8th inch diameter hole
The tension pins are rated for a certain size. I used 1/8th inch diameter pins for this, so they are actually a little bit bigger. The way they work is because of the larger size, they put a force on the hole, which keeps the pin in place. This may make it tough to hammer in, but they are very stable once in place.
7. Hammer in the 1/8th inch diameter tension pin
Pretty simple. You will notice there is a rounded edge on one or both ends of the pin. Place that edge in first, making sure it is lined up with the hole correctly. Take a normal, steel hammer (not a machinist's hammer) and begin hammering away. A machinist's hammer is bad because the pin is made of steel. You want to force the pin into the hole, not worry about whether you are going to damage it or not. Just be cautious you do not slip and accidentally hit the handle. It will deform.
8. File the pin to the correct dimensions
Once again, pretty simple. Take a diamond coated file and shave down those last 0.020-0.010 inches off. The pins I used were galvanized, which have a zinc coating on top of them to prevent rusting. I'm not worried about rust since there is oil in the gun blasted out by the nozzle (if you use green gas especially). Once again, this is a step you will be measuring quite a bit. You are working for an overall measurement of between 0.064 - 0.066 inches. Once you are done, clean up the shavings and dust with a paper towel (wet then dry).
That is it, once you have verified you have the similar dimensions to the stock part. Nothing else is needed to be done. If you bought pins that have a black coating on them, you can touch up the area you filed with some cold blue. Just make sure you know how to use cold blue, otherwise you will end up creating rust.
There you have it! A relatively straight-forward, simple to do mod for WE-Tech M4 patterned GBB replicas. I have a new surprise waiting for the next posting. I am just waiting for a few final parts to show up at my door. The weather is warming up in Western New York, so let the plastic slinging begin!
