MP5 Hop adjustment, changes whilst firing!

[Asomodai]

Hello all! 

I have a JG MP5SD6. Love the platform. The hop unit is something to be a bit miffed about! 

It's the MP5 type which is adjusted by a small lever at the top of the receiver. I love the idea behind it, however it seems fairly loose and whenever I fire, the recoil from the gearbox alone lowers the hop. 

Anybody else experience this? I am thinking maybe a washer or two on the mechanism to prevent it from moving, just wondering if there was a better or easier way? My mates JG MP5 does not have this problem despite being the same age (1 week old!) Unfortunately the MP5 seems to be one of the harder guns to take apart in my experience. Even getting to the hop unit and barrel means taking apart the receiver and removing the gearbox (Unless I am doing something wrong!)

Its a shame there is no true aftermarket replacement for this particular type of MP5 hop unit. 

View attachment 40377

 

[BigStew]

it's the marui style of hop actually one of their bad designs to easy to knock. you could swap over to ICS/G&G hope that uses a slider to adjust the hope similar to the ak hop

 

[Asomodai]

it's the marui style of hop actually one of their bad designs to easy to knock. you could swap over to ICS/G&G hope that uses a slider to adjust the hope similar to the ak hop

Doesn't the ICS Style of hop have to be adjusted through the side chamber? The JG Does not have that window unfortunately. 

 

[BigStew]

Doesn't the ICS Style of hop have to be adjusted through the side chamber? The JG Does not have that window unfortunately. 

Ok that's a bust then.

 

[Rogerborg]

Like this?

If so, that's also an example of SDS.  Mine has three cable ties whipped around it to keep it more or less in place, but I'm going to have to have it apart to introduce some more friction in there.

 

[Samurai]

Gorilla tape it to the outer barrel.

It's shit, I hate that on mine too.

 

[Davegolf]

I cut the lever down so it's flush with the top of the handguard, then wedge a tiny bit of butyl tape (like blutac but way better) behind it, the hop adjustment is then stiff and impossible to accidentally knock.

 

[Asomodai]

Thanks for your help gents! 

I have found an official product that may fix the issue. Its called a Strike Chamber and it will tighten the arm up using a rubber O-Ring and plastic attachment. In addition it includes a modified hop arm that apparently gives better shot consistency. Hell even if it doesn't work I have to open up the gun anyway to put these parts in regardless. If I need to add an additional washer then so be it! 

https://shop.ehobbyasia.com/first-factory-strike-chamber-for-marui-mp5-series-aeg.html

Unfortunately the shop was having a sale on other MP5 parts... Time to pimp this sucker out! More ramen to eat this month...

 

[Asomodai]

So after getting this installed by a tech, the lever adjustment is still happening. Within 3 seconds the hop effect is reduced to zero. Dare I say that I might be the only way to fix this Is to TDC mod it?

 

[HellmarineGR]

P90Greetings from Greece! 

Mp5 s hop up unit is shit.. I also have a jg sd6 and i m done the TDC mod and also rhop flat hop. I can hit targets 50cmX50cm at 65-70m with 0,3 bbs on a m110 spring and stock barrel.i can stand against higher value replicas easily... Ask me if you want to know what I'm done 

View attachment 72474

 

[heroshark]

When I had mine I cut it off and used a tiny dot of super glue to secure once set.

 

[HellmarineGR]

Same.. I measure and drill a hole and after I used some windscreen glue to stabilize two nuts and a screw going directly in homemade hop up arm... A lot of hours to customize but worth it... 

 

[Hatchet]

I have the Marui (well, it used to be a Marui) and the hop is one of the things I dislike about it most. The other being the fact you have to fully disassemble the gun to do *anything* to it.

I have often considered TDCing it, but you'd presumably have to go in through the top receiver and the charging handle/spring. I have avoided doing so because I'd undoubtedly balls it up.

You can obviously just set the hop and then remove the adjustment lever, but you still have the fundamental problem of the hop adjustment arm being on the same axis as the recoil (unlike rotary hops). I think the Classic Army B&T uses a rotary hop so that might be an option or go with another brand, but that's not technically "fixing" yours...

It is a slight mystery to me why nobody has made some sort of 3D printed solution to this (ala the MK23 hop). Guess MP5's just not that popular.

 

[HellmarineGR]

In mine mod the hop up arm - adjustment is 90° degrees and it can hope even 0,40bbs without any problem. Charging handle and spring isn't functional but if I have to choose between that and some great shoots, I go with the second.. The slap is lost... 

 

[Just Joe]

Sorry to hi-jack the thread a bit.

Interested in getting MP5SD6. Worried about the issues above as i'm not the most tech savvy.

Is this a relatively easy fix? I'm unsure what a TDC mod is.

Is it worth steering clear of the JG platform and option for CYMA because of these issues or are you likely to get the same?

 

[Hatchet]

A Top Dead Centre mod is where you have the pressure on the hop nub applied directly from above to avoid any misapplication of pressure (which can sometimes be caused with systems that use a side system to set hop, such as the VSR or the MK23). In most cases the hop nub is designed to be applied from the top, but changing the way this is done can give improvements. For example, on M4 hops or on AK style hops the recoil of the gearbox is on the same plane as the adjustment arm, which can lead to self-adjusting hop. This is why rotary systems like those found on the G3 can be more likely to keep their setting.

In some cases you can just use a shim/washer to allow you to tighten things down a bit more, but changing it to a TDC application (using a grub screw or similar) can also help. Some guns are easier to do this to than others.

With the MP5, the hop adjustment lever is exposed on the side of the gun as well as being on the same plane as the recoil, so it's not the greatest design. This can be mitigated to an extent by cutting the adjustment lever down and shimming. Both of these are easy to do and just require removal of the front handguard. A TDC mod on the MP5 would be technically challenging (unless you have crafting/3D printing skills or don't mind messing with the externals)

Everything else on the MP5 is a pain to do because you have to disassemble the entire gun every time (including things like changing the hop rubber, etc).

It also may depend on the specific brand - I think the Classic Army B&T models may have used rotary hop.

 

[Just Joe]

A Top Dead Centre mod is where you have the pressure on the hop nub applied directly from above to avoid any misapplication of pressure (which can sometimes be caused with systems that use a side system to set hop, such as the VSR or the MK23). In most cases the hop nub is designed to be applied from the top, but changing the way this is done can give improvements. For example, on M4 hops or on AK style hops the recoil.....

It also may depend on the specific brand - I think the Classic Army B&T models may have used rotary hop.


 

Thanks for explaining mate, much appreciated