Prowin M4 Hop Chamber Feeding Issues

[AG1212]

I've tried it in different AEGs and all have problems: in some it doesn't feed at all, in others it will feed but it will shoot with very low velocity. In others it will feed BBs into the hop chamber, but it won't shoot them with the hop on any setting, it sounds almost like a...fart noise for lack of a better description.

I've tried G&G, prometheus, systema and ACM hop rubbers and different nubs, as well as r-hop...any one know what the issue is?

[Vortix]

In what way is the hop unit pressed against the gearbox? With the screw it came with or with a bunch of O-rings around the barrel? I remember having some issues when the unit is not properly sealed to the gearbox. The O-rings will help. 

[Lone_Bullet]

Perhaps a short nozzle for the hop unit? Not feeding ans a massive airleak sounds a bit like that.

 

Sent from my C6603 using Tapatalk

[AG1212]

Yeah I was using the screw it came with, was pretty sure it was pressed as far back as possible though :/ Maybe it's the nozzles. Starting to doubt the appeal of the prowin hop...

[Vortix]

When it works, it works. I would start sealing it to the gearbox with rubber O-rings instead of the screw. You can get these at virtually any hardware store for a few Euros. Next step if that doesn't work would be to open up the gearbox and replace the nozzle. 

[Wingmann]

Don't use the screw. Find a spring that you can put around the inner barrel or o-rings as suggested.

[AG1212]

I'll give it a go, cheers.

[Black Knight]

I have these chambers in 10 different AR's(G&P, Lonex and Specna brands) and all work flawlessly. However, I noticed that with a Maple Leaf 70° bucking the chamber puts such pressure on the bucking lips, that you have to use force to get the bb through. This is obviously not good, as the tappet plate spring cannot push the bb forward hard enough, resulting in a "farting" noise upon firing, as described.

 

I found the "bb drop"- and "bb push"-tests described in this video very helpful, when playing around with hopups and different buckings: https://www.youtube.com/watch?v=156t4FrN2KA

[mimesis]

I know I have one of these in one of my several ARs, probably being used with G&G or G&P innards, with no problems.  Nothing fancy on the bucking or the inner barrel either.  If the unit is seating correctly (sometimes there's a mismatch between the "wings" and the slots they fit in), then the next culprit, as mentioned, is the tensioning on the unit (spring from a ballpoint pen, big but short spring around the inner barrel, or O-rings).  Failing that either the nozzle is faulty or there's some strange mismatch there.

[Wingmann]

AG1212, did you try all this with the buffer tube assembled? In some cases the long screw for the buffer tube pulls the gearbox to the back when torqued down, effectively pulling the nozzle away from the hop chamber and causing all kinds of issues.

[Colin_The+Ferret]

I got hold of a CA33 that was intermitently missfeeding. Put one of these in and it now feeds flawlessly

The screw does need some tweaking for a perfect fit. Madbull blue hop rubber and excel .2s.