Building My First HPA DMR (Surprise, It's a Kc02)

[Alimcd]

Good morning people!

 

I’d been looking for an excuse to have a crack at one of these for a while and when a used KC-02 came up in the classifieds; well, I thought it would be rude not to.

 

I’ve got a week coming up where my (much) better half is going to see her parents so I’ve gone ahead and ordered an enormous amount of stuff to arrive between now and then to capitalise on being able to work in the house and not the garage!

 

The used rifle had clearly had some loving but she’s going to get a whole new lease of life over the next couple of weeks.

 

If you’ve built one before, PLEASE step in to tell me when I’m doing something arse-backwards. If you haven’t, get ready to admire the shiny stuff that’s on the way.

 

Today, I’ve been forced against my will to go to work. As a fuck you, I’m going to try and convert the 2x CO2 mags to HPA in between emails and phone calls

[Alimcd]

The gun is a bit vanilla at the moment. Won’t be the case for long.

 

On to the mags, broke them down to their simplest and drilled a 4mm hole in the back. Tapped it with (can’t remember bit) and voila! Going to JB weld the bottoms and they should be pretty much done. 
 

Ive removed the part that pierces the bulbs btw and swapped out the outlet valves for normal gas mag ones, so they should behave fairly predictably

 

 

[Adolf Hamster]

So is this getting a pt3 or pt5 put on it? 😛

[Alimcd]

Nope (although that would be pretty cool) it’s getting a Boyds Blaster 

 

I think they’re gorgeous and that’s all that matters!

 

[Adolf Hamster]

Is it bad that i'm surprised?

 

That does look pretty sweet, a good choice

[Alimcd]

I saw a post on Arnies by RenegadeCow where he had used this stock. It was a work of art. I couldn’t figure out what the base pew was but I knew I wanted one.

 

Happened across Rogueworx and there it was. Doesn’t even seem like it’s going to be a tricky build (he says tempting fate)

[Adolf Hamster]

Yeah, it'll look like a target rifle, which tbf is a very appropriate look for the platform.

 

Extra points if you go full elmer fudd when fielding it 

[Alimcd]

Looks messier on the photo than it is in the flesh. Mags are done!

 

Now it’s a waiting game for stuff to arrive.

 

Geek-wise, the shopping list so far is:

 

Rogueworx Genesis hop up and nozzle

RW Piston

RW Bolt

RW charging handle

RW barrel spacers

RW mag release

Boyds Blaster stock 

Maple Leaf 380mm barrel

ML Decepticon 60

 

The previous owner had already switched out the hammer and sear for the MAG steel parts, so whilst I’d love to fiddle with it, the trigger box is done for now. I’m replacing the mag release as the current one seems a bit worn and the mags flap about a bit!

 

Resprayed the barrel and receiver before I left work. Have to wait until Monday to see if I did a half decent job. Scuffs are at least all covered up now!

 

 

 

[Alimcd]

Following a complete disassembly, it appears that the previous owner fitted an aftermarket rocket valve, presumably to reduce the output as he was running C02. 
 

I think it’s the RA-Tech one? I’ll post a picture in a bit. It’s got a few small metal discs on the end of it, I’m assuming that changing the mass affects the power? Anyone fitted or using one of these?

 

KJW aren’t shipping spares at the moment due to the ol’Rona so I’ll have to get everything working with this valve for now.

 

In more news, shipping confirmation for a parcel containing almost everything Rogueworx make

[Adolf Hamster]

discs are probably spacing, holding it slightly closed compared to standard, at least if it's working anything like the adjustable npas.

 

dropping back to stock would be my go-to given you're regulating the fps externally now.

[Alimcd]

Once I can find somewhere that carries them, I think that’s exactly what I’ll do

 

Heres the offending item in my patented “bag bits from the same part of the gun up until you’re so familiar with the insides that you can Chuck it all in a box together” technique 

Edit - tangential thought, in the background is a trusty FPS conversion table. Yesterday at site, I couldn’t believe I was hearing someone argue with a Marshall, having failed chrono as they could grasp that a 0.28@350 wasn’t the same as a 0.2@350. Do they not teach maths or physics in school anymore?

 

Edited May 24, 2021 by Alimcd

[Adolf Hamster]

Hmm, maybe not.

 

Tbh i'm not all that good with the gbb stuff, i just know they tend to be very finely balanced so generally the best option is not to mess with anything you dont have to.

[Alimcd]

For now, as long as it works, it’ll be fine. As you say, I can adjust velocity via my regulator.

 

Before I disassembled, I did run a few rounds through the chrono with Red gas. With the original 250mm barrel, it was 400,390,380fps/0.2 as the mag cooled. The 380mm barrel on the way is obviously going to push that significantly higher and the RW nozzle/piston combo should be more efficient so I might get away with the reg set at 85ish psi. in an ideal world, it’ll be great if I can get it consistent, giving 450/0.2eqv whilst lifting 0.43g at 95psi as that’s what I run my pistols at... 

 

Testing will commence later this week!

 

In more news, the paint job on the receiver and barrel has comes out rather well and the tired, scuffed finish is no more.

[Adolf Hamster]

Ooh yes that barrel is looking much nicer.

[Alimcd]

Cleaned out the trigger box, the grease inside had gone quite dark. Disconnector action is much snappier now

 

Its a bit of a faff to get the valve knocker spring seated back on the pin it goes on! That would have been much easier with a third hand. There’s doubtless a technique to doing it that I just haven’t picked up yet

[Alimcd]

RW Mag release, bolt carrier, charging handle and the Genesis nozzle installed.

 

Still not sure about that float valve but I won’t be able to test until my new inner barrel arrives. Slightly disappointed that Skirmshop uses Hermes, any other courier and It’d already have it!

 

Stock is due today between 12 and 1!

 

Oh yeah, forgot to say, that RW bolt carrier is smooth as butter to rack!

[Alimcd]

Unfortunately, it turns out I’m an idiot and haven’t bought a VSR style barrel (!) so this has currently not got a hop or inner barrel inside

[Adolf Hamster]

you know i think this might just atone for your previous m4 stock related sins.

 

that stock really does the world of difference.

[Alimcd]

It’s seriously comfy and the front end is so light. It practically aims itself

 

My other DMR requires you to be bloody Arnie to last a game

 

Cant wait to get that barrel in so I can do some tests. 

[Adolf Hamster]

it does look very handy to carry around.

 

just need a deer stalker, and a pipe now

[Alimcd]

I’ve stuck a Hi-Capa barrel in for now so I can check it cycles etc

 

What a way to test it😆

[Adolf Hamster]

If it works it works......

[Alimcd]

I can’t believe how much of a dopey twat I’ve been today. Left the air bottle at home too!

 

Ive bought a VSR style barrel from Bullseye, hopefully it arrives for the weekend

[Alimcd]

At 90psi and with a 5” barrel it’s giving me 210fps with 0.36g. Going to be interesting to see what a change to a 435mm barrel makes. 
 

Important thing is it cycles and feeds. If the output is too high, I’ve got the RW flow restrictors and PSI adjustment to compensate

 

Also, picked out my load out for the first game with it

[Adolf Hamster]

yes, i approve of this plan