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Building My First HPA DMR (Surprise, It's a Kc02)
- Thread starter Alimcd
- Start date
Adolf Hamster
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- Feb 1, 2018
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If it works it works......
Alimcd
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- Mar 31, 2020
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- Thread starter
- #24
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
View attachment 74248
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
View attachment 74248
Adolf Hamster
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- Feb 1, 2018
- 7,057
- 2,229
yes, i approve of this plan 
Alimcd
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- Mar 31, 2020
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- Thread starter
- #26
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!
View attachment 74303
View attachment 74304
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).
View attachment 74305
View attachment 74306
View attachment 74307
View attachment 74308
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!
View attachment 74309
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!
View attachment 74303
View attachment 74304
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).
View attachment 74305
View attachment 74306
View attachment 74307
View attachment 74308
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!
View attachment 74309
Alimcd
Members
- Mar 31, 2020
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- Thread starter
- #27
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!
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
Members
- Mar 31, 2020
- 693
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- Thread starter
- #28
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!)
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
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- Mar 31, 2020
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- Thread starter
- #29
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
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
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Alimcd
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- Thread starter
- #30
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!
View attachment 74447
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!
View attachment 74447
Adolf Hamster
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- Feb 1, 2018
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Alimcd
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- Mar 31, 2020
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- Thread starter
- #32
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
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
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- Mar 31, 2020
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- Thread starter
- #33
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
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
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- Mar 31, 2020
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- #34
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
View attachment 75988
View attachment 75989
View attachment 75990
View attachment 75991
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
View attachment 75988
View attachment 75989
View attachment 75990
View attachment 75991
Alimcd
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- Mar 31, 2020
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- #35
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
View attachment 76222
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
View attachment 76222
Last edited by a moderator:
Alimcd
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- #36
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
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
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Alimcd
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- #37
So, slightly delayed by work and life.
View attachment 78922
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.
View attachment 78923
View attachment 78924
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
View attachment 78925
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…
View attachment 78926
You won’t want to miss out. Join the dark side https://discord.gg/kqrxqvTC
View attachment 78922
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.
View attachment 78923
View attachment 78924
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
View attachment 78925
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…
View attachment 78926
You won’t want to miss out. Join the dark side https://discord.gg/kqrxqvTC
Last edited by a moderator:
Alimcd
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- #38
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
View attachment 80041
View attachment 80042
Some hack sawing and sealing later and it doesn’t swing around like a 2500rd pendulum under my gun anymore
View attachment 80041
View attachment 80042
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