[kevintk]

Greetings all! let me start by saying that I have taken quite a bit of time to creep around forums and learn to the best what I can. Many forum posts and youtube videos later, I come here, seeking the best possible help I can get.

My goal: Build a high FPS setup with superb compression, a good hop up system, and a sturdy motor/gear-set combo in hopes of creating an accurate gun at moderate distances (you've probably heard this a million times)

My current setup:

A long while back I had the gun worked on by Frank at Airsoft GI. This was before I was into teching, so there are a number of parts in my gun that have not been identified with any brand. (poor mistake...)

The gun currently chronos 400-405 with .20's with the hop-up turned all the way off.

-KWA M4 early 2GX model w/ 9mm ball bearings
-Stock hop up chamber
-stock 2GX hop up bucking
-Prometheus 450mm 6.03 inner barrel
-stock cylinder
-stock tappet plate
-stock spring guide
-stock air nozzle
-120 spring (I think)
-unidentified motor (might be stock)


IMG_1217 by http://www.flickr.com/people/kevintk/,

IMG_1215 by http://www.flickr.com/people/kevintk/,

IMG_1216 by http://www.flickr.com/people/kevintk/,

-unidentified piston (Might be airsoft GI PE poly carb piston)
-unidentified portless piston head
-unidentified cylinder head (maybe systema area 1000)


IMG_1249 by http://www.flickr.com/people/kevintk/,

-unidentified gear set (I'm am not sure what ratio they are or if they will even be suitable for pulling a strong spring)


IMG_1248 by http://www.flickr.com/people/kevintk/,

IMG_1237 by http://www.flickr.com/people/kevintk/,

Side Note: Upon opening the gun, there was only one shim in the whole gearbox. Bevel gear, nothing. Sector gear, nope. Spur gear, shim located on the top. Oddly enough, when I spun the spur gear by itself, it was making obvious contact with the ball bearings and I was surprised that a pro tech would do such a thing, but it worked. I switched the single shim to the bottom of the spur gear and it completely freed it of any contact with the bearings. My only guess is that when everything is back together, the spur sits neatly and doesn't need a bottom shim...

As you can probably tell, my gun is in a bit of disarray and I feel that it really needs to be taken to the next level.

This is where the fun begins

So with all that being said, I would like to focus on the new parts that I can put into this gun to turn it into a DMR weapon. I've picked each part based on reviews I've read and things I've heard, but I really need input on which parts to keep and which to ditch.

Hop-Up:
- Swap soft 2GX bucking for firmer king arms purple bucking.
- flat hop the king arms bucking
- install Hunter-Seeker R hop
- dental floss the bucking

Spring/Spring Guide:
- Guarder SP140 spring. banking on 470-480FPS
- Might stay with stock spring guide unless I'm convinced otherwise

Compression Parts:
I'm really not sure about which compression parts I should use. Any suggestions would be great

- G&P polyacetal high pressure piston
- Really need suggestions for piston head. What is the best head for a high FPS setup?
- Might do SHS or Guarder dual o-ring cylinder head with teflon tape
- Need suggestions for cylinder. I think I'm going to use a type 2 cylinder with the back ported. What about portless pistons? Need suggestions.
- I am also very curious about adjusting the AOE with a sorbopad. But it would be taking up a considerable amount of volume within the cylinder. FPS or proper alignment?
- Probably will stick with stick tappet plate unless convinced otherwise.
- Greatly need input on the air nozzle. I am very aware of how important the seal needs to be with the bucking. (I plan on supergluing the nozzle to the tappet plate)

Gear set and motor

- JG blue high torque motor

Gears are my number one concern right now because they have to be perfect. I can stick the existing gears, but I am not sure how they will hold. Nor am I sure about the current shimming. I am totally open to buying a new gear set,
but my KWA gearbox does not have conventional bearings. I may seek help from a friend who is very familiar with shimming all kinds of guns.
On a side note, does anyone have experience with the pre-shimmed guarder high-torque gear set?

Also, I plan on doing a MOSFET, but my only concern is the active braking. What kind of affect does the active breaking feature have on a motor that pisses torque? Any input would be great

So, to the experienced tech, how does all of this sound? Am I missing anything or is anything glaringly wrong? Any help, advice, or recommendations would be amazing.

Just keep in mind that I am shooting for a DMR setup, so if any of you have experience with building a smiliar gun or have done the same to a KWA, I would be greatful for any info.

Thanks!

 

[vindicareassassin]

First, you really need to read all of my sticky at the top of the page, and I mean right through to the section on tuning an SR, virtually the same except a v2.5 box. Its out of date now by a few years but still reasonabley relevant.

Always, always, correct your AoE, at the spring power and torque loads we play with your piston will die in pretty short order if you don't.


I don't recommend using sorbo as an AoE corrector, in combination with high load springs, as the sorbo will compress when its all together altering the AoE.


What I now do is mould an AoE corrector directly to my cylinder head out of silicon rubber, far more durable and less compressive, but still gives shock adsorbsion and returns to its natural state almost instantly.


If you plan on running the 450mm barrel you really need to run a 0type cylinder, even on full rear pull, and with a 6mm AoE corrector the overall volume is only just on the limit for that length barrel.


A brake fet will handle the power, especially if its made by an experienced EE, like terry at extreme fire, I've just finished the schematic and I'm just about to build a multi N channel and dual P channel fet with capacitor bank, to power my pre-cocking M21 project :nuts:

 

[kevintk]

First, you really need to read all of my sticky at the top of the page, and I mean right through to the section on tuning an SR, virtually the same except a v2.5 box. Its out of date now by a few years but still reasonabley relevant.

Always, always, correct your AoE, at the spring power and torque loads we play with your piston will die in pretty short order if you don't.

I don't recommend using sorbo as an AoE corrector, in combination with high load springs, as the sorbo will compress when its all together altering the AoE.

What I now do is mould an AoE corrector directly to my cylinder head out of silicon rubber, far more durable and less compressive, but still gives shock adsorbsion and returns to its natural state almost instantly.

If you plan on running the 450mm barrel you really need to run a 0type cylinder, even on full rear pull, and with a 6mm AoE corrector the overall volume is only just on the limit for that length barrel.

A brake fet will handle the power, especially if its made by an experienced EE, like terry at extreme fire, I've just finished the schematic and I'm just about to build a multi N channel and dual P channel fet with capacitor bank, to power my pre-cocking M21 project :nuts:

Thanks for the suggestions. I have read through a few of the stickies but I will make sure to look through them thoroughly.

Regarding the AoE adjustment, is there a detailed explanation on how to create the silicon buffer on the cylinder head? I would imagine it needs to be a very even surface.

Also for the AoE: Is the removing of the back two piston teeth completely necessary when adjusting the AoE? Wasn't sure so I thought I'd ask.

I'm still wavering on the type 0 cylinder. I've read about guys doing experiments between the type 0 and type 1, saying that guns around the M16 length with good compression tend to get better results with the type 1. And for the piston head, do you think a POM head would be suitable for a high FPS setup?

 

[vindicareassassin]

There isn't an explanation anywhere yet as I only devised it in the last 6 months. Its quite easy to do if you have any experience using domestic silicon sealant, if not its a bit more tricky.


Basically you need a former (mould), like an old cylinder, with you cylinder head inserted in it the wrong way to a depth of about 6mm, apply release grease to the cylinder walls, then inject the silicon onto the head making sure you fill it properly, with no air bubbles, then take a straight edge and a long round tool, I use a knitting needle, and plenty of good, old fashioned spit, tool up the silicon to be flat and level with the cylinder edge, and mould in a tapered port into the nozzle tube, set aside to cure for atleast 48 hours, then remove it from the former...... Job done!



Removal of the 2nd, half the 3rd, & occasionally part of the forth will always need to be done, if you don't you'll get pre-engagement and stripped gears.


A 1type cylinder will be fine if you never plan on using anything heavier than .25 BBs, if you want to use heavier you need to maximize your compressable air, hence only use a 0 type cylinder.


I'd only ever consider a 1 type cylinder if I were to use an M4 363mm barrel, but even then I'd use a 0 type and do the maths and drill my own balancing holes.

I'm even doing experiments with a volume maximizer, similar to an airbrake, but longer and thinner, to try and get a usable volume closer to 1/1.9, barrel to cylinder, using a 430mm barrel

 

[1tonne]

I normally use a type0 cylinder if I have an inner barrel of 450-550mm.
Or like Vindicareassassin said, do the math and port it yourself to get the best cylinder to barrel ratio

 

[solarisjock]

nice thing about type-0 cylinders, if it is to much you can always port it yourself to match your system exactly.

 

[kevintk]

Thanks a lot for the input, guys. Really appreciate it.

After looking at a number of online retailers, I've narrowed my selection down to these parts.
It would be great if you guys could look over these and make any remarks or suggestions.

- R-Hop Z kit
- King arms hard purple bucking (flat-hopped)
- dental flossed bucking
- Prommy 450mm 6.03mm (already installed)
- Guarder SP140 spring
- stock KWA spring guide
- JG blue high torque motor
- seigetek balanced ratio gears w/ systema shims (already installed)
- Guarder super lucid cylinder type 0
- Lonex cylinder head
- lonex air nozzle
- G&P high-stress polyacetal piston
- Modify or Guarder POM piston head, maybe matrix mushroom head. Need help deciding
- stock tappet plate (worth upgrading?)
- adjust AoE with silicon sealer mod and removal of piston teeth.

 

[solarisjock]

I would swap the G&P piston for a lonex Red. Also use RTV silcone gasket maker instead of the Dental floss. that way you have Zero airseal issues between bucking and barrel. I also have been using the Prommy Blue flat hop buckings to great effect.

 

[kevintk]

I would swap the G&P piston for a lonex Red. Also use RTV silcone gasket maker instead of the Dental floss. that way you have Zero airseal issues between bucking and barrel. I also have been using the Prommy Blue flat hop buckings to great effect.

I've looked around and cannot buy any lonex parts other than the cylinder head and the air nozzle. I found a Canadian retailer with a variety of parts, but they can't ship to the U.S.

I'll make sure to look into the silicone gasket mod before I do anything to the hop up.

Also, how can I make sure my air nozzle makes a perfect seal with the bucking?

 

[1tonne]

The JG blue high torque motor is an excellent motor for the price.
Where are you getting it from as most places are out of stock. Do you have a link?

 

[kevintk]

The JG blue high torque motor is an excellent motor for the price.
Where are you getting it from as most places are out of stock. Do you have a link?

Evike has them I think airsoft GI has them as well:

http://www.evike.com/product_info.php?products_id=29435

 

[vindicareassassin]

Also, how can I make sure my air nozzle makes a perfect seal with the bucking?

I double line mine with a brass tube that slides into the cylinder head nozzle glued into the sliding nozzle, then lube with thick silicon grease.

This provides as perfect a seal as your ever going to get at the gearbox end, at the hop end you can either shoulder it, which requires you to have a slightly longer nozzle to start and machine a shoulder into it that presses against the hop rubber lip, or just flatten the nozzle front so it does a similar thing to the shoulder nozzle, but this can give you feed issues if you get it wrong :shrug: