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Tp Custom Gunwerx Kac Pdw


targetpractice

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For my first true custom build (no for real, this isn't a build to mess with Endgame for once), I will be building a KAC PDW, using the externals of a VFC, Dboys gearbox and miscellaneous internals.

 

This project started after my short experience of hauling around Harvest's RPG during Blind Fury. It didn't turn out very well (in fact, I only carried it for half an hour) due to the bulk of my gear, rifle and the RPG. After swearing off carrying a heavy weapon, I won a Tactical Tupperware Noobtube launcher, which was half the weight and easier to operate. It still did not eliminate the other issue, that of carrying a large rifle, so I started looking for a new weapon. After some research, I decided to get a KAC PDW, since it would based on the more familiar AR platform and I wouldn't have to get new magazines, as opposed to an MP5, MP7 or P90-based PDW.

 

I liked the VFC one, but was quite expensive at $400. I was about to order a DBoys/Bravo RDW when I found a listing for a VFC PDW upper and lower receiver for $60. After some quick research, I realized I could build one to my specification for far below $400, possibly under $200.

 

This album is a journal of this build that would hopefully show others new to AEG building the processes involved, as well as solicit feedback and discussion from the more experienced builders here.

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Here are the externals as is: complete upper and lower without the proprietary parts such as ambidextrous mag and bolt release buttons, side clip, grip and flash hider.

 

PDW001.jpg

 

I did a search for these parts without much luck, and I ended up contacting VFC about purchasing these parts. They returned a quote to me for $135 before shipping, and this excluded a gearbox ($65 new from Dboys). This wasn't looking for my prospects of a sub $200 PDW. Fortunately I found a lower receiver with gearbox for $50, with all the proprietary parts (missing a single pin holding the left bolt release catch). The wires on the gearbox were cut and the receiver was in bad shape, but for the most part would provide me with $200 worth of parts.

 

PDW002.jpg

 

After a week, I got the donor receiver:

 

PDW003.jpg

Edited by targetpractice
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When building projects such as these, it is important to plan ahead, especially when working with boneyard parts. Having the parts breakdown goes a long way in figuring out whether this project will be worth the money and having everything you need on hand when it's time to put things together.

 

PDW004.jpg

 

I marked out the needed parts in orange, and parts to be removed or omitted in pink.

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Along with your usual pins, mallets, screwdrivers and lubes, one very important item in your toolbox should be little plastic baggies to separate and store parts. I like to separate the parts by assemblies and bag them together, unless they are fragile parts. I also mark the bags in case they get mixed up with other similar parts:

 

PDW005.jpg

 

Also super useful: a magnetic parts bowl. I found that out the hard way at my first Chill N' Grill. I own two of these, and you can get them super cheap at your local Harbor Freight.

 

PDW006.jpg

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After some finagling, I managed to get the gearbox out of the receiver. Despite appearances, this is not a standard V2 gearbox. Most of the differences are on the left side. To my surprise, this gearbox has 7mm bearing bushings.

 

PDW007.jpg

 

There are several holes on the gearbox that go right through, such as the one above the trigger - that one secures the gearbox to the receiver, and another is used to thread the axle of the ambidextrous selector. There is also a recess for one of the selector gears to sit in (under the arch on the selector plate). Note that the selector plate is also slightly different from your typical M4. It is made of sheet metal much like the material in the back of PC cases (zinc?) and from my understanding is known to be a point of failure when the selector stops working. The plate on this was slightly bent, so I took it out, cleaned it, took care of the bend and re-mounted it. Note that the selector gears have already been removed.

 

PDW008.jpg

 

Upon closer inspection before removing the selector gears, I found two dead bugs squished under the selector plate!

 

PDW009.jpg

Edited by targetpractice
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Gearboxes tend to have screws of varying lengths, so I tend to lay the screws and any washers out around the gearbox, pointing at the holes where they go in, and take a picture before I store the screws away. I can also use the picture as a reference to make sure I have everything when it's time to put it back together.

 

PDW010.jpg

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Now that the screws are put away, it's time to pop open the gearbox. Don't forget to stick in a small screwdriver into the rear of the spring guide, to prevent the spring guide from releasing and shooting its way out when you pop the gearbox open. It'll also keep your gears, shims and other parts from popping out. Does anyone know what the deal is with the window on the gearbox, by the way?

 

PDW011.jpg

 

Spring release, gearbox opened. At this point, I always take a good photo of the gearbox, to mark the position of the gears (good for troubleshooting if the gearbox had issues to begin with), and also to mark out any proprietary parts in there as well. I work in IT, and I document a lot of stuff so this is more force of habit but is a good practice either way.

 

PDW012.jpg

 

The internals have the usual amount of heavy grease atypical of Dboys and JG, along with a bit of dirt. I noticed that the first tooth on the sector gear that engages the piston has a small chip on it - improperly shimmed, maybe? In either case I would consider replacing the entire gear set if I can find set at a reasonable price.

 

PDW014.jpg

 

Another part of the gearbox disassembly that I document thoroughly are the number of shims originally placed when this was first put together. This would come in handy for determining whether this was properly shimmed to begin with, troubleshooting and also as a guide for putting it back together, if it were indeed shimmed properly to begin with. Good thing I did, the spur gear on this had two shims. Don't forget to take a photo of the shims on the opposite side! As per my practice the parts were bagged and labelled.

 

PDW013.jpg

 

Finally, as I was disassembling the trigger assembly, the red wire came off the contact. The soldering was not that great on this. The battery lead wires were cut off and the fuse was missing to begin with, so I knew I was going to dispose of this anyway. I will probably replace this with an SHS or Guarder wire and switch set. Airsoft is a hoarder's dream so I bagged the entire trigger assembly, including the bad wires, just in case.

 

PDW015.jpg

 

The trigger itself had lost a fair amount of paint and was chipped. I was starting to get the impression that this AEG had been run over by a truck.

 

PDW017.jpg

 

The trigger appears to be structurally sound, and in order to save $10-$20 on a new trigger, I plan to strip the paint off, repaint it and remount it. The chips and gouges appear worse without the paint on it. I will break out some sanders and buff the gouges out, and maybe fill the deeper ones with epoxy and rebuff. I only stripped the paint off the visible part of the trigger as the rest is hidden in the gearbox anyway.

 

PDW018.jpg

 

At the end of the day, I am left with this pile of parts:

 

PDW016.jpg

 

At this point I spend some time evaluating whether I need to replace anything. I'm debating on whether I need to replace the sector gear as the chip is very small. The gun will be downgraded to fire below 350fps, down from the original 400fps so there will be even less strain on the internals anyway. To my surprise the spring guide also has bearings. Most of the parts are of decent quality and I will probably retain as much as possible to save on the costs of rebuilding. The only other part I will replace is the nozzle, as it was slightly deformed.

Edited by targetpractice
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Another objective of this project is to run the gun without an external battery. The gun originally ran its battery through a PEQ box, which was quite large in comparison to the size of the gun and also tended to ruin the sleek lines of the gun in my opinion. To do that, I had to remove the entire outer barrel assembly, which is free-floating, and removed the faux gas tubes and gas tube holders (the black cylinder that looks like a hop-up bucking). While the aluminum-colored gas tubes were cool they got in the way of installing an intenal battery and it won't be seen much once a rail cover is put over the rails.

 

By taking out the gas tubes I believe I can run a pair of 100x20x6mm nunchuck lipos in the handrail.

 

PDW019.jpg

 

Well, that's all I have for now, folks. Parts need to be ordered, so it could be a few weeks before this is updated again. It will be constantly updated through the winter, though.

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At this point, I'll still need the following to get it functional:

 

Motor, long or short type

Grip cover if I want to keep the look of the original smaller grip, complete grip if I go with a long motor.

Trigger assembly and wiring

Dean's connector (and battery)

Inner barrel, 229mm

Hop-up unit

Hop-up bucking

M90 spring

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At this point, I'll still need the following to get it functional:

 

Motor, long or short type

Grip cover if I want to keep the look of the original smaller grip, complete grip if I go with a long motor.

Trigger assembly and wiring

Dean's connector (and battery)

Inner barrel, 229mm

Hop-up unit

Hop-up bucking

M90 spring

 

You would need a medium type motor for the stock pistol grip.

 

I have some 229mm barrels btw

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^What duder said. The original grip used the annoying sig medium motor, just get a standard ar grip and run a long type motor.

 

Looking good so far TP! looking forward to continuing to help you get her off the ground!

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If you could make it sexier than this,

pdw_main.jpg

Yeah, that would be nice....

 

Make us proud, hombre. You can do this.

Edited by Endgame
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^What duder said. The original grip used the annoying sig medium motor, just get a standard ar grip and run a long type motor.

 

What was so annoying about the motor?

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TP, I highly suggest a APS wiring and trigger assembly, I've had one in my G36 for about 2 years never had a problem with it. And its made very well.

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TP, I highly suggest a APS wiring and trigger assembly, I've had one in my G36 for about 2 years never had a problem with it. And its made very well.

 

Like one of these, correct?

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Like one of what? lol.

 

Whoops! Forgot the link :lol:

 

OK, this: http://www.evike.com...oducts_id=34506

 

The APS ins definitely in consideration. I'm also looking at an SHS. As I'm in no real hurry to finish this, I'll probably order from Hong Kong and sit out the 2-4 week shipping time.

Edited by targetpractice
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