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

[Alimcd]

While I’m waiting for a barrel to arrive, might as well let anyone interested know what I think/what I’ve done.

 

Firstly, getting a real 10/22 stock onto the KJ receiver? Very easy.

 

I had to remove c.1.5-2mm from either side of the outerbarrel mount, chamfer the bottom of the magwell and remove the rear tang from the receiver. On the Boyds stock, I had to widen the rebate for the trigger box by roughly 1mm either side.

 

Whilst it would have been quicker with a dremel, I wanted to be as precise as possible and went with a hand file. All in, it took around half an hour to get the receiver in the stock. It’s solid as a rock with no play!

Initial thoughts on the Rogueworx parts?

 

As I haven’t been able to get stuff running as I want it yet (bought the wrong barrel, didn’t I!) my oppinio  as yet can only be based on the tolerances and fit of the bits I purchased.

 

The only comparable products I’ve had the pleasure of mucking around with, built to this standard are Retro Arms gearboxes and Combat Union hop units. The way that the charging handle and bolt carrier mate is totally precise with no slop or wobble. For comparison, the previous bolt would snag unless you pulled the charging handle from the bottom.

 

The RW nozzle glides inside of the carrier. A little bit of superlube and it was smooth as silk. The ported RW piston also seems to do exactly what it says on the tin. The supplied O-rings fit “just-rightly not too tightly” inside of the nozzle. I suspect that this is going to be a very consistent mechanism (as long as the RA tech NPAS that’s in there isn’t a bag of wank).

Finally, I couldn’t live with having two mags with rear HPA taps and one downwards facing so I forced my lazy arse to do a proper job on the gas mag!

[Alimcd]

Barrel arrived! Testing it out, it seems like I’ve been very lucky. At my magic 95psi I’m achieving 375fps w/0.28 (don’t want to do lots of testing with 0.43, ouch!) with is pretty much bang on the money for my site limit of 450/0.2g.

 

Problem is, the consistency is not all that great. Whilst I was regularly getting 366-375, there was the odd reading in the 350’s. There’s a fair bit of play in the magazines, so I’m assuming that it’s the router to nozzle fit that’s causing the issue. I’m going to put a bit of electrical tape around the lip on the back of the mag and pad out the sides of the magwell. 
 

Let’s see what a bit of bodging can achieve!

[Alimcd]

Oh, forgot to say. The Genesis hop and its nub are basically one of the best toleranced pieces of kit I’ve seen in Airsoft. Once lubed, the nub fits perfectly into the hop unit’s aperture. Putting some pressure on the nub with a screw reveals the most symmetrical pressure on a hop rubber Ive ever seen.

 

If I can work out why I’m getting the deviation, this thing should be seriously effective 

 

(was going to say accurate, but no pew is “really” very accurate beyond 30m if there’s foliage and wind at play!)

[Alimcd]

I worked out what was causing the odd really low output

 

The knocker lock was quite worn and wasn’t always fully retracting the knocker. 1 in 10 shots, it was partially retracting and likely reduced the force with which it hit the outlet valve. A few strokes with one of the wife’s old Emery boards and it’s back to doing what it’s meant to.

 

I’m actually surprised at how little material I had to remove to solve the issue

Edited May 30, 2021 by Alimcd

[Alimcd]

Managed to get her down to a +-5fps deviation now. Going to nip into work tomorrow to pick up my valve tool - just want to make sure the inconsistencies aren’t down to the KJ outlet valves 

 

Can’t wait to see how far she can send 0.43g’s

 

Re: Photo, the Cat destroyed a cardboard box. I’ve got wood floors going down on Tuesday. I’m not just a total slob!

[Adolf Hamster]

10 hours ago, Alimcd said:

Photo, the Cat destroyed a cardboard box. I’ve got wood floors going down on Tuesday. I’m not just a total slob!

 

cat's expression says it all.....

[Alimcd]

Did a little bit more testing in the garage. I think I’ve worked out the final piece of the puzzle!

 

The knocker lock was causing big round to round deviations, I’ve discovered today my homemade hop wheel tensioner was slipping thanks to the recoil and the power output was gradually creeping up as the hop lessened. I’ve filed the piece a bit sharper now and the hop wheel is staying put.

 

2 long mags, 374-378 with 0.28’s @95psi. I’ll have to wait to get it to Finmere to set the hop correctly for 0.43’s and then tune my psi accordingly for the site limit

[Alimcd]

Had my first game with the KC02 on Sunday, learned a few things about the build.

 

1.) My hop wheel tensioner was rubbish. I’ve made a new one from a biro nib and it’s giving a far more positive click for each adjustment.

 

2.) The KJ plastic rail is rubbish and at one point I had to push my scope back to zero! I’ve got a metal RA tech one arriving soon but I had to buy an entire new outer barrel to get it! £140 oof

 

3.) When the hop wheel was in the right position, this thing sends BB’s a long way. 
 

4.) 90rds is not enough to get through a 2 hour game. I need to find a KC02>MP5 HPA adaptor

[Alimcd]

May as well update this in case someone wants to build one. 
 

Bored of waiting for a TanukiWorks HPA adaptor restock and unwilling to pay for extra magazines I got creative.

 

Turns out the width of the standard KC02 mags and the collar of the top of the G&G M4 drums is almost identical. With not much more than fitting the Bowden spring into the KC02 mag and epoxying the mag into the drum - the KC02 HPA drum mag was born! 
 

I ran a test of a few hundred rounds and it feeds perfectly and is as consistent as one would expect with HPA. I was worried about the sheer weight of the thing in the mag well but it seems to be a non-issue

[Alimcd]

Having picked up the donor gun secondhand for this build, I assumed the super-heavy trigger pull and fairly high amount of force required to set the hammer was normal for a KC-02.

 

I was wrong

 

The previous owner had installed the MAG 150% steel hammer set & spring. Chatting to Arron at Rogueworx, not only is the 150% spring unnecessary, the parts are arguably worse than the stock ones.

 

On recommendation, I’ve bought his hammer set and he’s donated me a standard hammer spring. The difference in spring strength is insane, the bolt has almost no resistance in setting the hammer now. The sear is insanely sensitive now, I had to remove a fraction of material from my disconnector hook (three or four strokes with a file) and now the trigger is light as a feather. 
 

Unfortunately, he’d sold out of his adjustable trigger so it’s still the stock one. Once he’s made more, that’s definitely on the list so I can adjust the travel of the trigger to take the slop out after it breaks.

 

Here’s a quick peek at the new parts in and my lovely pointy finger applying almost no pressure. 
 

(I’m almost certainly going to accidentally shoot myself with this) 

 

EDIT - Does the softer hammer spring affect output velocity? Doesn’t seem too, still got a zip tie through my reg and still a gnats fart under 1.88J with 0.43’s. The only observable difference in output is that consistency has improved with my biggest deviation over 100rds this morning being about 7fps

Edited July 17, 2021 by Alimcd

[Alimcd]

Just in case anyone wondered what had happened to me. I’m not dead. I was enticed over to the KJ Owners discord where Arron of Rogueworx resides.

 

Ive picked up some more pretty awesome bits for this particular gun. Should be able to get some photos later. 
 

Rogueworx are having a big restock in late Oct/early Nov for anyone interested in building a tricked out KC02

 

https://www.rogueworx.com

 

Hail Saustrich

Edited September 17, 2021 by Alimcd

[Alimcd]

So, slightly delayed by work and life.

 

 

I picked up something that has made my KC02 either a semi auto DMR at 1.8J or a single action sniper at 2.32J.

 

Its called the Rogueworx SSB, and as you can see from the pictures, it differs significantly from the standard reciprocating bolt by being one solid piece. The loading nozzle is integrated into the bolt and there are no moving parts. The output power of the SSB is adjusted by a grub screw that obstructs the hole on the front of the nozzle (Apparently, fully open with a decent length barrel and C02 it’ll give about 5J). Once adjusted, I’m dialled in to be comfortably under my site limit WITH 0.43’s. I didn’t realise quite how much this joule creeps until I stopped being a cheapskate and stopped chronoing with 0.28/0.36’s and started using my actual ammo.

 

Consistency is +-1fps with my HPA rig. 
 

Changing the bolts takes all of 2 minutes; all you need to do is remove the action from your chosen stock, separate the trigger box from the upper, pull back the charging handle and remove the bolt. 
 

Did I mention it’s basically silent? The action of the Rogueworx Judgement hammer is significantly quieter than the incumbent stealth king MK23. Racking the charging handle is as loud as you want to make it 

 

The RW Genesis hop kit replaced the KC02’s proprietary hop system with a VSR style chamber using a TDC hop and three differently shaped hop keys to best apply tension to your choice of bucking. I’m using a concave key that gives amazing results with my trusty ML Autobot 60*
 

I hadn’t realised how adaptable the KC02 platform was when I first stepped in but thanks to (actual Rolls Royce Engineer) Arron Stafford’s friggin brilliant work and anally retentive attention to detail, the RW parts are a step up from anything else I’ve purchased in Airsoft in terms of design or realisation. 
 

Hail Saustrich 

The next gun RW will be transforming is the GHK G5. It’s going to end up with a TDC hop, steel fire control group, lightweight alu bolt… 

 

 

You won’t want to miss out. Join the dark side https://discord.gg/kqrxqvTC

Edited September 18, 2021 by Alimcd

[Alimcd]

The harshest criticism can be the most useful! After it was pointed out that my gun and my drum mag were not technically in the same postcode I decided to go all McGuyver.

 

Some hack sawing and sealing later and it doesn’t swing around like a 2500rd pendulum under my gun anymore

[Albiscuit]

Its beautiful, great build.

I appreciate but dont like the drum mag though but thats just my opinion.

[Alimcd]

19 minutes ago, Albiscuit said:

Its beautiful, great build.

I appreciate but dont like the drum mag though but thats just my opinion.

Honestly, I hate drum mags. There’s an HPA adaptor for the KC02 called a Tanuki that I’ve been trying to get hold of for months, the V4 will hopefully be out soon and it’ll let me use my MP5 midcaps with this build

[Albiscuit]

I get it, I usually use hi caps or drum mags where possible as I cant be arsed to carry loads of mags, it just looks wrong in a dmr, I use smgs so kinda get away with it.

 

Appreciate the effort and engineering though, decent thread.

 

And that stock... beautiful

[Alimcd]

It’s got a sibling now thanks to @Cromulon1994

 

 

The Muzzelite is bang on 1.8j@100psi and semi auto locked, the Boyd has the Bolt action bolt in and is tuned to 2.32j@100psi

Had to get creative with the Muzzelite, it’s a real stock for a normal 10/22, and the trigger reset distance is quite different. I took a couple of mm of material off the front of the trigger to give it a smidge more travel and now the sear can reset each time.

 

Looking forwards to hearing the whispers in the queue for chrono trying to figure out what this is!

 

Edit - thanks autocorrect

Edited October 16, 2021 by Alimcd

[Alimcd]

This thing is so cool. 

[Albiscuit]

My gawd its ugly.

 

 

I love it!!

[Alimcd]

The looming deadline for the Rogueworx underlever kit has made me do something financially irresponsible. Underlever kit now on order, The Muzzelite stock is for now in my spares box and this Hogue Overmold has arrived ready for my underlever 

I’m going to be keeping an eye on the classifieds for the next boneyard KC02 so I’ve got a receiver and trigger box to stick in the Muzzelite. It’s too unique and too ugly to not take to the field. Got a mate working on a solution to make the trigger less, well, bullpuppy too

Edited November 5, 2021 by Alimcd

[Alimcd]

I had a laugh at the evolution of my play style over the last 2 years - from 40rps DSG wankery to almost exclusively semi-auto with a hint of bolt action

[Impulse]

4 minutes ago, Alimcd said:

I had a laugh at the evolution of my play style over the last 2 years - from 40rps DSG wankery to almost exclusively semi-auto with a hint of bolt action

 

As a totally unbiased onlooker, I believe you have reached peak airsoft.

 

No, don't look at how I play, that has nothing to do with it!

[Alimcd]

1 hour ago, Impulse said:

 

As a totally unbiased onlooker, I believe you have reached peak airsoft.

 

No, don't look at how I play, that has nothing to do with it!

Not sure about you, but I had to massively up my pistol game to be able to run the semi-auto or bolt-action play style and not get caught out when people get inside of my minimum engagement. I got a little round of “nicely done” from some dead enemy players couple of weekends ago when I took out the last AEG player who was dug into some cover with my KC tucked under my right arm, firing the pistol with my left. More luck than anything, but I landed one on his baseball cap before he could get a bead on me. Big grin behind my mask!

Edited November 5, 2021 by Alimcd

[Impulse]

2 hours ago, Alimcd said:

Not sure about you, but I had to massively up my pistol game to be able to run the semi-auto or bolt-action play style and not get caught out when people get inside of my minimum engagement. I got a little round of “nicely done” from some dead enemy players couple of weekends ago when I took out the last AEG player who was dug into some cover with my KC tucked under my right arm, firing the pistol with my left. More luck than anything, but I landed one on his baseball cap before he could get a bead on me. Big grin behind my mask!

 

It's the advice I always give people who want to get into sniping: get a solid sidearm first! You'll need it. I often joke that I get 1 kill with the rifle and about 10 kills with the pistol each game. It's also part of the reason I kept my m21 and spring VSR to 1.1J, as I'll generally run the HPA VSR if I want 2.3J and an MED, though even when using my 1.1J BASR, I still get more pistol kills even without an MED!

 

I'm currently in the process of upping my game and improving my trigger discipline. Transferring completely away from AEGs in favour of GBBRs (because they're so fun to shoot, I can't go back...), so getting used to 35rd magazines there, but I also may be buying a Tanaka m700 this weekend (another "I don't want to buy anything, but I can't pass up the opportunity" situation, since Tanaka rifles are loooooong out of production) and those gas sniper rifles only run a whopping 10rd magazine, 28rd if you get the extended ones, though I'll be keeping to the short ones.

 

Yeah, you get less "kills" playing like this, but it's so much more satisfying. As a German dude told a teenage me back in Spain when I used to play there: it's not how many you hit, but how you hit them.

[Alimcd]

I did a thing, a financially irresponsible thing. 
 

a mate is turning me a custom tapered barrel and the DMR action is going to be housed in this…