Jamming.

[Muffin]

Aright, so some of you may know my custom build: Airsoft Canada
I recently aquired a Guarder 6.04 tightbore to use with my barrel extension. I removed my CQB barrel and swapped the hopup unit, put it back together and test fired.
First few shots fired nicely, others seemed to drop fast, until it sounded as if I was firing through a silencer, however it was not firing.
I took out the inner to see a BB stuck at the start of the rubber. I took it out, tried it again with the same results.
I put the CQB back together and everything works great. Whats the deal with my longer barrel?

Much appreciated.

[Thenooblord]

its possible that the hopup rubber isnt fitting properly with the new barrel and is causing it to become misplaced during use and jam

[pusangani]

yep definitely hopup rubber issues, sounds like farting?

[Styrak]

+1 for a hopup rubber issue. Take apart the hopup and make sure it's seated correctly as well as the nubbin.

[Muffin]

Everything seems to sit correctly, I don't see a difference between the 2 barrels. The nub is in the correct place. I'll try the swap again and see if it is sitting incorrectly.

[cbcsteve]

Can be Outer barrel problems

Big Note: I matched the Cylinders to the correct barrel length and correct porting

THAT sounds exactly what happened to me when I added a longer inner barrel to my
P90 and MP5K. I am guessing cause the innards near the hop up area were not reinforced to hold up a longer inner barrel as it is heavier and makes the tip droop a fraction lower.

I never found out why. But now I think I have an idea which I should have tried but the longer inner barrel is gone so I have cannot test it out but try this.

1. Take off the outer barrel and just have the inner barrel showing.
2. Hold the inner barrel and try to push it a little upwards and see if it shoots. Try it in different ways upwards, downwards, side to side.

Cause when I thought about it I used a silencer to cover the longer inner barrel but my guess is that it so long that its causing the hop-up to move just a fraction downwards causing the farting noises. And the silencer did not really provide a tight hold on the inner barrel.

So I am guessing the hop up area in your CQB gun is either not made to hold up longer inner barrels.

or

The outer barrel you have may not be tight enough to reinforce the inner barrel to be straight. (I don't know how tight that outer barrel is, just a guess since my silencer had no cushioning of the outer barrel whatsoever)

All Mad Bull 6.03 Barrels

MP5K Testing
When I put a M4 (363mm) Barrel length on my MP5K it seemed to shoot oddly but still okay
When I put a AK-47(455mm) barrel length on my MP5K it farted and did not shoot.

P90 Testing
When I put a AK-47 Barrel length (455mm) it shot well but still seemed odd I could hear something strange like it was not shooting 100%
Then I put on the original P90 Barrel (247mm) it shot and sounded better.

[MADDOG]

If you have not changed the cylinder from CQB setup (the ported cylinder hole will be near the front) there may not be enough air pressure generated to force a BB down a significantly longer barrel.

You need to match your cylinder type to your barrel length or you will get extreme BB drop off like you are seeing. That is why it works fine with the CQB barrel and not the longer one.

[Muffin]

Thanks alot for all the suggestions. I had no idea that cylinder types could cause this. As per your suggestions cbcsteve there is no difference with the outer off. I've realized that the first few shots seem to fly nicely(5-6rnds) then after that some start to drop quickly or slice, then the always wonderful jamming.
Upon yet another swap I learned that hopup holes on the barrel are also differently shaped. I'm unsure if this has anything to do with my issue but I'd some more insight on it before I whip out my Dremel.
The bronze colored barrel is my CQB(left) and the silver is my 455mm(right).

[cbcsteve]

Aaahh so that might just be it!

Now that I think about it my MP5K barrels had a different cut than the AK barrels so the hopup unit in the MP5K was probably only made to accept the MP5K style barrels or that style of "cut"

Perhaps see if you can borrow another friends Hop up unit to test it out. Or dremmel could work. Cause whats happening with you happened exact same way to my gun shoots great and then starts farting and I never figured it out. I am interested in seeing what happens next. If the dremmel works then adding longer barrels instead of getting a whole new gun would save so much money

[BeAcH]

If things still dont work after all this maybe you should try a madbull barrell. I have never had a problem with using their barrels.

best of luck

[Muffin]

I dremeled the opening on the tightbore so it was the same size as the CQB, but nothing different. I put the tightbore in my buddies carbine of which seemed to handle it better, probably had twice the amount of consistant shots that I did. But after about 20 rounds they dropped, sliced and then jammed.

[cbcsteve]

Just like MadDog was talking about are you using a Type 0 Ported Cylinder (450 - 590mm Barrels)

http://www.airsoftparts.ca/store2/in...roducts_id=776

One last thing to check have you tried putting that 455mm in a AK-47 and see how it runs.

[conrad13]

I had a farting issue similar to yours when I got a madbull inner barrel and G&P houp unit my my M16. For me it turned out that the G&P rubber was just a hair small and would jamb the BBs. I replaced the with a stock TM rubber and eveything was fine.