Jump to content


What did I do wrong? Bucking suggestions! Prometheus Tightbore & M120 spring


  • Please log in to reply
74 replies to this topic

#1 rawfuls

rawfuls

    Enthusiast

  • Members
  • PipPip
  • 37 posts
  • Country:

Posted 29 June 2013 - 04:34 PM

Okay, excuse the incredibly ghetto chrono, but before putting everything through, stock barrel & spring, I was imbedding BB's into somewhat thick cardboard.

After the M120 spring (with stock barrel), I was piercing cardboard, and able to make a circle cutout on full auto (by spraying).

After M120 spring and tightbore, I'm not only piercing paper, and just leaving an imprint on the cardboard.

Obviously I did something wrong with the tightbore swap.
I'm thinking something with the bucking, I may have pinched a few holes into it..

With a Prometheus Tightbore @ 6.03mm and Prometheus M120 spring, what kind of bucking should I be purchasing?

Any help would be greatly appreciated.
Stock hop-up (however if needed, could upgrade..rather not)

This is on a KWA M4 CQB model, with a 363mm barrel (barrel extension)

Edited by rawfuls, 29 June 2013 - 04:35 PM.


#2 vanevery

vanevery

    Specialist

  • Members
  • PipPipPip
  • 959 posts
  • Gender:Male
  • Country:

Posted 29 June 2013 - 05:32 PM

It could be the barrel and nothing you did wrong.
Prommy's are known for issues in KWA guns.
I could not tell you exactly why that is.
What Cylinder do you have in your gun?
What Main spring did you previously use in this gun?
What was the previous chrono reading?
How does the gun actually shoot with each barrel?
What bucking are you using?

Edited by vanevery, 14 July 2013 - 06:37 AM.


#3 gcw360

gcw360

    Supreme Guru

  • Super Moderator
  • PipPipPipPip
  • 11,309 posts
  • Gender:Male
  • Location:New Jersey
  • Interests:Airsoft (Especially repair and customizing), Fly Fishing, Fossils (Especially Dino), Snakes, Photography
  • Country:

Posted 29 June 2013 - 05:55 PM

Like Van alludes to, it sounds like the barrel isn't a good match for the hop-up and bucking.  Changing the bucking isn't necessarily the answer.  You need a barrel that is compatible with the hop-up/bucking combination you are using.  I recommend the KM Head 6.02.

#4 rawfuls

rawfuls

    Enthusiast

  • Members
  • PipPip
  • 37 posts
  • Country:

Posted 29 June 2013 - 07:46 PM

Everything was stock until I put in the new M120 spring and this tightbore.
Main spring was stock.
Previous chrono reading was roughly 360s-370s, I want to say.
The gun shot amazing with the stock barrel, I decided I wanted to try out a tightbore because I noticed the accuracy wasn't TOO great at a bit more range.
Bucking is stock.

The reason why I'm leaning towards the bucking is because I DID do a foolish, dumb mistake.
When I stuffed the barrel into the bucking (which was in the hop up unit), the bucking at the end got smush. Of course, being a newbie, I put the entire thing back together, tried to fire- and it didn't.
Obviously, because part of the  bucking was blocking the barrel.
Again, foolishly, as a newbie, I trimmed what was sticking out (took the bucking out, trimmed the coupling part off, and a little more to keep it a little shorter as for it not to happen again), and stuffed it back in, and that's when I noticed it.
Of course, I used the scissors as I was getting a little anxious and also because I was in a somewhat hurry.

Should I pull the prommy tightbore out and just go with the KM Head ?
I'd rather not considering it's already here...

Thanks!

EDIT: Basically, I used the red part of the bucking (illustrated below).
And cut at the blackline.
Posted Image

Edited by rawfuls, 29 June 2013 - 08:10 PM.


#5 EzDeezer

EzDeezer

    Enthusiast

  • Members
  • PipPip
  • 55 posts
  • Gender:Male
  • Country:

Posted 29 June 2013 - 08:30 PM

The back is what creates the seal around the nozzle, so that would probably explain it.  Id still leave it to see what someone else says, but im like 99% sure that your problem is that you cut off the part that actually creates the seal, and kept just the other rubber part.(If I understand what your picture means too)

#6 Icurblud

Icurblud

    Enthusiast

  • Members
  • PipPip
  • 95 posts
  • Gender:Male
  • Location:Pennsylvania
  • Country:

Posted 29 June 2013 - 08:59 PM

So your saying you cut the front of the bucking down?  If. That is what you did then your bucking is trash now.  You have no seal for the bb's.  buy a new bucking and you should be fine.

#7 rawfuls

rawfuls

    Enthusiast

  • Members
  • PipPip
  • 37 posts
  • Country:

Posted 29 June 2013 - 09:16 PM

That's what I imagine.

Would the seal cause that drastic of a FPS?
After I cut the bucking, I could definitely see the BB's falling a LOT after they left the barrel; as if they didn't have a strong enough push (since the seal is gone?)

#8 EzDeezer

EzDeezer

    Enthusiast

  • Members
  • PipPip
  • 55 posts
  • Gender:Male
  • Country:

Posted 29 June 2013 - 09:34 PM

Since the seal is gone,  lots of air is escaping (loss of FPS), you may have also cut out the mound in the bucking, this would result in lack of hopup (another cause for BBs just dropping after a few feet) you will need a new bucking, next time take your hopup chamber apart when installing a new barrel (I think the prometheus will be fine, but may just be a tight fit) taking the chamber apart ensures that your nub and everything else go in correctly (without the nub you get no hopup, no hopup=very very bad range).  I believe there is a guide on taking it apart pinned in the downgrades and modifications section.

Edited by EzDeezer, 29 June 2013 - 09:35 PM.


#9 gcw360

gcw360

    Supreme Guru

  • Super Moderator
  • PipPipPipPip
  • 11,309 posts
  • Gender:Male
  • Location:New Jersey
  • Interests:Airsoft (Especially repair and customizing), Fly Fishing, Fossils (Especially Dino), Snakes, Photography
  • Country:

Posted 29 June 2013 - 10:12 PM

It's time to get a new bucking.  If the 2G KWA bucking does not yeild a good result with the Promi barrel then I would look for a TBB that is made for the gun like an EDGI ot KM Head.

#10 vanevery

vanevery

    Specialist

  • Members
  • PipPipPip
  • 959 posts
  • Gender:Male
  • Country:

Posted 30 June 2013 - 07:43 AM

A new bucking is definitely in order.
My guess would be your install may have been a bit difficult due to the tight tolerance of the KWA Hop-up Unit. Your Prommy barrel may have a larger Outer Diameter than a stock KWA barrel.
If you have difficulties installing, try a few drops of this on the bucking and in the Hop-up tube:
Team Associated 100% pure silicone oil / 30wt. http://www.rcplanet....l_p/asc5422.htm
Most hobby shops sell pure silicone oil. In the hobby world it is known as Shock Oil.
Try something around 30wt.
Also:
The front of the bucking is where the bucking lips are that seal with the air nozzle.
The back of the bucking is toward the C-clip area.
You can trim the bucking at the back if need be, but you would not want to trim the front where the air seal is.
Try a new KWA stock 2g bucking.
Always good to have one on hand when new to working on your KWA guns.
You may want to also consider buying an after-market standard bucking with a standard mound.
A basic Lonex 50 Degree bucking would be a good choice or any standard drop-in bucking that is soft rubber should serve you well.
Keep us posted and I am sure you will get your gun up to speed.
We are all here to help each other out.

Edited by vanevery, 30 June 2013 - 07:43 AM.


#11 rawfuls

rawfuls

    Enthusiast

  • Members
  • PipPip
  • 37 posts
  • Country:

Posted 30 June 2013 - 07:02 PM

Sweet guys!
It's a good thing I still race RC, I've got plenty of that shock oil laying around!

If it's not the bucking.. could it be the Prometheus barrel?
Just swap that out for the KM Head 6.02?
Should I swap the KM Head 6.02 for the Prometheus 6.03 anyways since I'll have some downtime waiting for the new bucking?

Thanks for the quick help guys, I love it!

#12 EzDeezer

EzDeezer

    Enthusiast

  • Members
  • PipPip
  • 55 posts
  • Gender:Male
  • Country:

Posted 30 June 2013 - 10:02 PM

Its for sure the bucking, but if it still really does not work than yes you may need to switch barrels, though I don't think the outer diameter on them is too big for the KWA hopup chamber.

#13 rawfuls

rawfuls

    Enthusiast

  • Members
  • PipPip
  • 37 posts
  • Country:

Posted 30 June 2013 - 10:44 PM

It looks like evike is out of the bucking, and only KWAUSA's Pro Shop has the bucking in stock.
Is there any other aftermarket that would work equivalent if not better than the stock bucking?

At about $8.50 for shipping for a piece that is the size of a quarter..what a pricey mistake.

#14 EzDeezer

EzDeezer

    Enthusiast

  • Members
  • PipPip
  • 55 posts
  • Gender:Male
  • Country:

Posted 01 July 2013 - 11:19 AM

I really like the G&G green bucking, but you may see some overhop with lighter than .30g BBs, its also a bit difficult to fit into the hopup chamber compared to the 2GX but it does work.  I have also tried the lonex 70 but do not like it as much as the green, I also find it even more difficult to install than the green, but it will work.  Others have had success with many different buckings, but your best bet might just be another 2GX for now, as it will be the easiest to install.

Edited by EzDeezer, 01 July 2013 - 11:19 AM.


#15 vanevery

vanevery

    Specialist

  • Members
  • PipPipPip
  • 959 posts
  • Gender:Male
  • Country:

Posted 01 July 2013 - 02:33 PM

Some of these are out of stock where I link them, but if you search around, you can probably find them in stock somewhere.

ICS Hop Up Bucking
http://www.airsoftgi...roducts_id=7669
Prommy Purple
http://www.evike.com...oducts_id=31081
Lonex 50 Degree Bucking
http://clandestineai...king-p-259.html
G&G Green Bucking
http://www.evike.com...oducts_id=36022

#16 rawfuls

rawfuls

    Enthusiast

  • Members
  • PipPip
  • 37 posts
  • Country:

Posted 01 July 2013 - 05:40 PM

Uh oh.. not again..

In the G&G Green Bucking picture, the thinner tube... (pictured below).
What is this exactly?
This fell out and I just tossed it. :(

Great, maybe next time I should leave it to the pros, but I guess learning first hand is learning the best way!
If I order the bucking from KWAUSA's pro shop, will I sitll need to buy this smaller tube/nub?

Posted Image

#17 gcw360

gcw360

    Supreme Guru

  • Super Moderator
  • PipPipPipPip
  • 11,309 posts
  • Gender:Male
  • Location:New Jersey
  • Interests:Airsoft (Especially repair and customizing), Fly Fishing, Fossils (Especially Dino), Snakes, Photography
  • Country:

Posted 01 July 2013 - 05:50 PM

View Postrawfuls, on 01 July 2013 - 05:40 PM, said:

Uh oh.. not again..

In the G&G Green Bucking picture, the thinner tube... (pictured below).
What is this exactly?
This fell out and I just tossed it. :(

Great, maybe next time I should leave it to the pros, but I guess learning first hand is learning the best way!
If I order the bucking from KWAUSA's pro shop, will I sitll need to buy this smaller tube/nub?

Posted Image
That would be the nub.  It is what applies downward pressure to the bucking that results in hop-up.  It is necessary and needs to be replaced.

#18 vanevery

vanevery

    Specialist

  • Members
  • PipPipPip
  • 959 posts
  • Gender:Male
  • Country:

Posted 01 July 2013 - 05:51 PM

You are going to need that.
That is the Nub.

The Nub is a small oval rubber piece of rubber that sits in a place holder on the Chamber Arm inside the Hop-up Chamber.
As you raise and lower the Hop, the Chamber Arm raises and lowers.
When the Chamber Arm lowers, it presses this Nub into the Bucking and pushes the Bucking Mound through the Barrel Window (more lift).
When the Chamber Arm raises, it releases pressure from the Nub and the Bucking Mound retracts(less lift).

Your Hop-up unit in stock form will not function without the Nub.
I think all of the Buckings I suggested and previously linked come with a replacement Nub.
So you will be ok if you order any of these Buckings.

Edited by vanevery, 01 July 2013 - 05:51 PM.


#19 rawfuls

rawfuls

    Enthusiast

  • Members
  • PipPip
  • 37 posts
  • Country:

Posted 03 July 2013 - 07:24 PM

Got the G&G Green Bucking (all that I remembered) when I stopped by a local airsoft place.

Installed it.
Has a LITTLE green poking out at the end w here the retaining clip goes.
Figured it'd be fine, assembled it.

Shoots awesome!
Although, with hop fully off, it still drifts upward.
What could that be?

Otherwise, it's shooting again! Woo!

Noticed motor and battery got hot... time to upgrade the motor!

#20 gcw360

gcw360

    Supreme Guru

  • Super Moderator
  • PipPipPipPip
  • 11,309 posts
  • Gender:Male
  • Location:New Jersey
  • Interests:Airsoft (Especially repair and customizing), Fly Fishing, Fossils (Especially Dino), Snakes, Photography
  • Country:

Posted 04 July 2013 - 06:49 AM

View Postrawfuls, on 03 July 2013 - 07:24 PM, said:

Got the G&G Green Bucking (all that I remembered) when I stopped by a local airsoft place.

Installed it.
Has a LITTLE green poking out at the end w here the retaining clip goes.
Figured it'd be fine, assembled it.

Shoots awesome!
Although, with hop fully off, it still drifts upward.
What could that be?

Otherwise, it's shooting again! Woo!

Noticed motor and battery got hot... time to upgrade the motor!
Could be the BB weight....what gram are you using?




1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users