Madbull Hop Up Chamber woes

[Krydel]

Hi guys,

 

So the night before a game at the mall last weekend I decided to install my Madbull 'Ultimate' hop unit into my G&P MOE after some difficulty.

 

At first, I could not get the hop bucking/rubber to fit inbetween the inner barrel and the chamber, as it was ludicrously tight. With a small amount of silicon, i got it on, but the included blue shark rubber was being stretched out into the cutout left for the c-clip, however careful we were. A friend suggested cutting a very small piece of the hop rubber and we managed to put it all together okay, c-clip and all. 

 

Next up was having to dremel the wings on the side of the chamber a bit so it would actually slot into place in the upper receiver (a common problem, from what I can tell after a bit of research) but this wasn't too much of an issue. I've taken enough off so you just have to apply a tiny amount of force and it slots into place. Not sure if it should go in and out easily.

 

Now at the mall, I started to have feeding issues - it would feed loads then none at all, or miss BBs periodically. Either way, a complete mess and unplayably bad. If i push the magazines upwards they will feed okay as of course does turning the rifle upside down.

 

At first, i took the BB o'ring off the bottom and this made no difference - BB's are getting into the chamber fine and are not being blocked, which to me means that there's something else going on.

 

Could this be something to do with the hop rubber difficulties I had going on, or something else? I can't put the stock G&P rubber in because the fit is so loose the chamber can move freely.

[AceOfSkulls]

Madbull 

 

Theres your problem.

 

I had that chamber and i couldnt get it to work. Im sure others have and will be able to help.

[PMO Gordo]

Madbull hop up has a notorious tight chamber, which requires thin buckings. If you use thicker buckings, such as Madbull's (how ironic - their buckings don't work with their own hop up), Prometheus, and etc, they tend to sit wrong in the hop up and cause jamming. One way to test if the buckings are seated right is to manually push a BB through (remember to dial the hop up off first). If it takes more force to push a BB through compared to your previous hop ups, there's a problem.

 

I recently tried Angel Custom's W bucking, and it worked well. Before that, I was using some generic black buckings that came with stock guns. They are all thin buckings.

[Mike 8-{>]

I had very similar problems with the barrel and hop rubber not fitting together I found that they work just fine with the aluminium madbull barrels which are a smaller OD than other after market or OEM barrels. That said after a lot of fettling and tweaking I never got it to work in my VFC M4. Eventually tried it in a CA AR15 and it just dropped in and worked first time.

[Krydel]

Thanks for the responses thus far.

 

I had it apart today and put the stock rubber into the madbull unit and there was loads of play - put some PTFE tape around to pad it out and seemed to fit a lot better (quite well, in fact). Alas, plenty of hopping issues.

 

I put the madbull shark rubber into my stock hop unit and as suspected, it feeds absolutely fine.

 

Any suggestions for alternatives? I'm guessing one of the blue CNC prowin ones will do me fine? Its a shame really, i only spent the £50(!!!) on the madbull for the BB retention and the LED unit really. Nothing stopping me cutting a channel in the side of a new unit to do the same job i suppose.

[skoda]

I found the problem is the lip at the back of the madbull chamber seems to be a bit too big for the hole at the front of the g&p gearbox.

[Wingmann]

The ProWin units will serve you nicely.

[blam360]

+1 for prowin hop up chambers. have replaced most of mine with prowins

[3vi1-D4n]

Fitted a madbull hop unit with a 6.01mm madbull 650mm barrel.  Ironically the madbull blue rubber didn't fit.  A guarder rubber fits snugly.