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Barrel upgrade...or not


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#1 nameless

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Posted 25 May 2009 - 01:07 PM

I ordered my KWA G36C on March 29 from evike.com (I do not recommend buying from them, by the way).  It's worked fine (other than a strange lack of hop up, but I'll get to that), but today I decided to install a Systema inner barrel and see if that increased fps/accuracy.  Specifically, 285 mm long (just slightly longer than the stock G36C barrel...less than 40 mm difference I believe).

The first thing I noticed when I took the gun apart was that KWA installed the inner barrel upside down, so that the opening in the barrel for the hop up wasn't lined up and the hop up was doing nothing.  Pretty weak quality control, guys.   :angry:

Also I noticed that mine does not have the 2G bucking.  Not that I expected it to.

Anyway, with the stock bucking and Systema barrel my fps went way down.  Before I was getting at least 350 fps with .25s, and after it was dropping below 300  :blink:   The Systema barrel seemed to be quite a tight fit, so I wonder if it was causing some kind of loss of compression.  Surely the marginal difference in barrel lengths wouldn't cause such a drop in fps (right?).

I ended up putting the stock barrel back in, and the fps was back to where it was before.  I would like to put a tightbore barrel in this gun at some point, along with a 2G bucking.  Any recommendations for brands/lengths that work well with this gun?

#2 Wintersx866

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Posted 25 May 2009 - 02:19 PM

View Postnameless, on May 25 2009, 04:07 PM, said:

I ordered my KWA G36C on March 29 from evike.com (I do not recommend buying from them, by the way).  It's worked fine (other than a strange lack of hop up, but I'll get to that), but today I decided to install a Systema inner barrel and see if that increased fps/accuracy.  Specifically, 285 mm long (just slightly longer than the stock G36C barrel...less than 40 mm difference I believe).

The first thing I noticed when I took the gun apart was that KWA installed the inner barrel upside down, so that the opening in the barrel for the hop up wasn't lined up and the hop up was doing nothing.  Pretty weak quality control, guys.   :angry:

Also I noticed that mine does not have the 2G bucking.  Not that I expected it to.

Anyway, with the stock bucking and Systema barrel my fps went way down.  Before I was getting at least 350 fps with .25s, and after it was dropping below 300  :blink:   The Systema barrel seemed to be quite a tight fit, so I wonder if it was causing some kind of loss of compression.  Surely the marginal difference in barrel lengths wouldn't cause such a drop in fps (right?).

I ended up putting the stock barrel back in, and the fps was back to where it was before.  I would like to put a tightbore barrel in this gun at some point, along with a 2G bucking.  Any recommendations for brands/lengths that work well with this gun?
You may have gotten a airleak from the C retainer clip that was leaking air cause of the new designs or something.  Or it may have just been that your barrel is a little bigger/smaller so it causes an airleak.  For the barrel being upside down, if you think this was bad G&G messed my friends gun up so much more.  The motor wires he got were not even formed correctly and had to be tighten within a minute of fully auto.  He also got a hop up that some dude tighten up so bad that it was nearly to the point of cracking and you couldn't even turn the dang thing.  His barrel was also messed up and looked like the inside had been shredded with something to the point where his accuracy was okay but WAS MISSING AT 80 FEET!

#3 Guest_allizard_*

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Posted 25 May 2009 - 04:38 PM

It's pretty abnormal to receive one with barrel installed incorrectly.  We usually spot check every batch when we receive them from factory.  Anyway, as for compatible barrel, have you tried KM head or Guarder?  Mind fit perfectly.

#4 nameless

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Posted 25 May 2009 - 06:15 PM

View Postallizard, on May 25 2009, 04:38 PM, said:

Anyway, as for compatible barrel, have you tried KM head or Guarder?  Mind fit perfectly.

Are those both 6.04?  I would rather try 6.03.

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Posted 25 May 2009 - 08:34 PM

View Postnameless, on May 25 2009, 07:15 PM, said:

Are those both 6.04?  I would rather try 6.03.

Not a whole lot of different performance in terms of 6.04 vs. 6.03 to tell you the truth.  Your BB's actually matters more.

#6 Spiggy

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Posted 26 May 2009 - 09:37 AM

View Postnameless, on May 25 2009, 07:15 PM, said:

Are those both 6.04?  I would rather try 6.03.
at that short length, the difference is negligible.  

I usually don't recommend a tightbore in these extremely short weapons unless your options are down to nothing and you're strapped for power.  It's not supposed to be a sniper rifle.

#7 Stealthmaster14

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Posted 05 June 2009 - 08:19 PM

As far as the FPS drop, not that many ideas..  Make sure the barrel is clean and the bucking didn't get ripped during installation.  

You should have gone with a PDI barrel.  They are only like 60 for G36C length.

Spiggy-How come?  I would think that with a short barrel, you would want the best accuracy possible since your range will not be quite as good as longer barrel guns.

#8 Jawz

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Posted 10 June 2009 - 10:01 AM

View Postnameless, on May 25 2009, 02:07 PM, said:

[...]

The first thing I noticed when I took the gun apart was that KWA installed the inner barrel upside down, so that the opening in the barrel for the hop up wasn't lined up and the hop up was doing nothing.  Pretty weak quality control, guys.   :angry:

*LOL*  The same happened to me, and I was so puzzled why my BBs would still drop after only 50 feet with the hop up fully engaged!!

Quote

Also I noticed that mine does not have the 2G bucking.  Not that I expected it to.

Anyway, with the stock bucking and Systema barrel my fps went way down.  Before I was getting at least 350 fps with .25s, and after it was dropping below 300  :blink:   The Systema barrel seemed to be quite a tight fit, so I wonder if it was causing some kind of loss of compression.  Surely the marginal difference in barrel lengths wouldn't cause such a drop in fps (right?).

From my experience, barrel length *does* matter!  I also own several ICS M4s, and one of them is an M4 CQB Pistol.  The inner barrel of that shorty is only 187mm long -- uh, "short" ;).  In order to get 400 FPS with it, I would need to use an M130 spring, which is not difficult to exchange since I have several upper gearboxes.  As soon as I install a G36C length inner barrel (247mm), which is my current setup, an M120 spring would get me to 400 FPS.

Long story short:  YES, barrel length does matter!  You probably know as well that you should pair up the correct cylinder (that has the correct porting) with the corresponding barrel lengths, right? ;)

Jawz

#9 nameless

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Posted 10 June 2009 - 10:14 AM

View PostJawz, on Jun 10 2009, 11:01 AM, said:

You probably know as well that you should pair up the correct cylinder (that has the correct porting) with the corresponding barrel lengths, right? ;)

Yes.  But I wouldn't think such a small difference in barrel length would matter in that regard.  It's not like I tried a barrel that was 200mm longer than stock.

Anyway, I've decided to stay with the stock length, in part so that I don't have to sweat stuff like that.  KWA has already put the correct cylinder in the gun, so I'm not going to mess with it unless I have to.  I've got a stock-length Prometheus 6.03 on the way.  Hopefully that will give me better results.

#10 nameless

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Posted 10 June 2009 - 10:17 AM

View Postallizard, on May 25 2009, 09:34 PM, said:

Your BB's actually matters more.


Bio BBs are required where I play.  I always use the Excel .25 bios, which are supposed to be the best bios available.  Does KWA have any plans to make bios?

#11 nameless

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Posted 14 June 2009 - 02:04 PM

View Postnameless, on May 25 2009, 01:07 PM, said:

Before I was getting at least 350 fps with .25s, and after it was dropping below 300  :blink:

I tried a Prometheus 247 mm inner barrel and the same thing happened.  What gives?

#12 gcw360

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Posted 14 June 2009 - 02:14 PM

View Postnameless, on Jun 14 2009, 06:04 PM, said:

I tried a Prometheus 247 mm inner barrel and the same thing happened.  What gives?

I had this problem with an EDGI 6.01 and 2G bucking in my M4.  After disassembling the hop-up and reinstalling the barrel it worked fine and I was back up to the FPS I had expected.  Can't hurt to recheck your work and re-chrono.

#13 Jawz

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Posted 15 June 2009 - 01:57 AM

View Postnameless, on Jun 10 2009, 11:17 AM, said:

Bio BBs are required where I play.  I always use the Excel .25 bios, which are supposed to be the best bios available.  Does KWA have any plans to make bios?

My team and I are using Airsplat's Bio BBs:
Airsplat 0.25g bio BBs

We just switched to bio BBs, and I would guesstimate that probably 60-80,000 rounds have been fired without any jams.  Accuracy is very good, too -- at least I cannot complain.  But the best thing:  They are cheap compared to other brands!  :D

View Postnameless, on Jun 14 2009, 03:04 PM, said:

I tried a Prometheus 247 mm inner barrel and the same thing happened.  What gives?
A completely different thought:  One thing that "newbies" sometimes forget is to re-attach the tappet plate spring back onto the corresponding post after an internal upgrade or simple maintenance.  Oh well, I just did this "rookie" mistake twice last week! *grrr*

You can get this issue confirmed by looking into the feeding tube (or just remove the entire magwell) and watching the air seal nozzle while firing in semi-auto.  If the nozzle barely or does not move at all, then you know you it's the tappet plate spring ;).

Of course, if you have never even accessed the GB's internals, my above suggestion is obsolete.  Then we have to look for a significant air leak somewhere else...

Jawz

Edited by Jawz, 15 June 2009 - 01:59 AM.


#14 nameless

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Posted 15 June 2009 - 07:03 AM

View PostJawz, on Jun 15 2009, 02:57 AM, said:

Of course, if you have never even accessed the GB's internals, my above suggestion is obsolete.

All I have tried to do is change the bucking and inner barrel.

#15 gcw360

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Posted 15 June 2009 - 07:10 AM

View Postnameless, on Jun 15 2009, 11:03 AM, said:

All I have tried to do is change the bucking and inner barrel.


Just a thought, is the spring that attaches to the top/front of the hop-up in place and is it functioning correctly?

#16 nameless

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Posted 15 June 2009 - 08:53 AM

View Postgcw360, on Jun 15 2009, 07:10 AM, said:

Just a thought, is the spring that attaches to the top/front of the hop-up in place and is it functioning correctly?

If you mean the one that pushes the whole thing back towards the gearbox, then yes it's in place and yes it's functioning correctly.  After I slide the inner barrel into the outer barrel assembly and turn it, the spring pushes the whole inner barrel and hop up back towards the gearbox.  Seems to be just fine.

After I put the stock inner barrel back in my fps went back up to normal, so I'd think my actual disassembly/assembly or the thing isn't the culprit.  Of course I could be wrong.

#17 Jawz

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Posted 15 June 2009 - 09:01 AM

View Postgcw360, on Jun 15 2009, 08:10 AM, said:

Just a thought, is the spring that attaches to the top/front of the hop-up in place and is it functioning correctly?
+1

gcw360 addresses a VERY good point!  Again, remove your magwell, turn your G36C upside down, and push (or "pull" -- depending on how you see it) lightly against the hop up chamber and it should jump back.  To make it clear what I mean, here's a picture from a non-related topic:

Posted Image

In the above picture, you can see the black hop up chamber with a blue rubber sleeve on the left side, and the gearbox with the air nozzle is on the right side.  If you put your finger between the above and push the hop up chamber towards the left, the latter should return to its original position *if* you have the spring properly installed or if the hop up chamber is not somehow stuck.

And again, fire a few blanks in semi-auto and see if the above air seal nozzle actually moves forward to the rubber sleeve and makes contact with it.  If you have a gap between the two, you know where the air leak comes from ;).

Jawz

*edit*
You already answered to the former post while I was typing...

Edited by Jawz, 15 June 2009 - 09:03 AM.


#18 Jawz

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Posted 15 June 2009 - 09:09 AM

View Postnameless, on Jun 15 2009, 09:53 AM, said:

After I put the stock inner barrel back in my fps went back up to normal, so I'd think my actual disassembly/assembly or the thing isn't the culprit.  Of course I could be wrong.
Hmm, very interesting...

Can you take pictures from several angles of the hop up/prometheus barrel assembly and post them?  I am particularly interested in the area of the hop up clip -- some people call it "C-clip" or "barrel clip:"  It's that black C-shaped plastic thinggy with the 3 "thorns" that holds the inner barrel.

Jawz

Edited by Jawz, 15 June 2009 - 09:09 AM.


#19 gcw360

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Posted 15 June 2009 - 10:30 AM

View PostJawz, on Jun 15 2009, 01:09 PM, said:

Hmm, very interesting...

Can you take pictures from several angles of the hop up/prometheus barrel assembly and post them?  I am particularly interested in the area of the hop up clip -- some people call it "C-clip" or "barrel clip:"  It's that black C-shaped plastic thinggy with the 3 "thorns" that holds the inner barrel.

Jawz

Ok, how are you installing the bucking?  Are you completely disassembling the hop-up to remove the barrel and finaly the bucking, or are you simply sliding the barrel and bucking in or out of the hop-up.  This is exactly what the issue was with my EDGI 6.01.  Only when I disassemble the hop-up, installed the bucking on the barrel and then reassembled the hop-up did the FPS return to expected.  If the bucking/barrel interface is making for a tighter fit in the hop-up, then I think your bucking is moving and not allowing the air seal that you need.  That's assuming you are not completely disassembling the hop-up.

See: Taking your Hop chamber apart.. in "Upgrades and Modifications" for an awesome description on the proper way to remove the barrel and disassemble the hop-up.  Please note: sometimes the fit of the barrel and bucking are such that it you are careful you don't need to do a complete hop-up take down.  However, at least in my case, it is.  This will also help you to ensure that the nub is in the proper place/alignment.

Let me know if this helps.

#20 gcw360

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Posted 15 June 2009 - 10:31 AM

View PostJawz, on Jun 15 2009, 01:01 PM, said:

+1

gcw360 addresses a VERY good point!  Again, remove your magwell, turn your G36C upside down, and push (or "pull" -- depending on how you see it) lightly against the hop up chamber and it should jump back.  To make it clear what I mean, here's a picture from a non-related topic:

Posted Image

In the above picture, you can see the black hop up chamber with a blue rubber sleeve on the left side, and the gearbox with the air nozzle is on the right side.  If you put your finger between the above and push the hop up chamber towards the left, the latter should return to its original position *if* you have the spring properly installed or if the hop up chamber is not somehow stuck.

And again, fire a few blanks in semi-auto and see if the above air seal nozzle actually moves forward to the rubber sleeve and makes contact with it.  If you have a gap between the two, you know where the air leak comes from ;).

Jawz

*edit*
You already answered to the former post while I was typing...
Thanks for the recognition.




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