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New hop rubber misfeeding and huge fps variations

  • Thread starter Thread starter JinxDuh
  • Start date Start date
Adolf Hamster said:
in some pews the feed lip length can be problematic, but i wouldn't say a stock e&l is one of them.
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I have never had a problem with the feed lip length in any of the 14 AK type weapons of various makes that the lad and I own between us; M4s and a few others have been a different story.

I also found a couple of the earlier AK2M4 nubs to be a little off; a bit of trimming did the trick.

 
Colin Allen said:
I have never had a problem with the feed lip length in any of the 14 AK type weapons of various makes that the lad and I own between us; M4s and a few others have been a different story.

I also found a couple of the earlier AK2M4 nubs to be a little off; a bit of trimming did the trick.
Click to expand...
What part did you trim? Never had to do that before 

 
the newer ones all factory mold.  I do check each before sending out but worth double-checking.  trimming the edges might help with you since it will reduce the height a tad, it's such a tiny amount though.  try a maple leaf one though and let us know if that makes any difference

 
Colin Allen said:
have never had a problem with the feed lip length in any of the 14 AK type weapons of various makes that the lad and I own between us; M4s and a few others have been a different story.
Click to expand...


Yeah i was talking more generally, not just ak's.

 
I think it's just a problem of the sliding AK/MP5 hops being a pain in the ass - I had to shave down my XT nub to stop my MP5 overhopping 0.28s with no hop applied as it was just a little too wide to fit the tract properly and was getting forced in when the arm went back in place [and the one I cut on the game day on a bench outside fixed this, just it was a little pissed so it was shooting to the left ?], a fresh XT nub same as the one you linked went in fine after some sanding and a little trimming, same ML macaron rubber too - just in a CYMA MP5 instead of an AK [the hops are pretty similar or at least I'm assuming so]

 
Stuck a stock black rubber in with the xt nub, fps variations from 270 - 298

Stock black rubber and nub (From an old m4 I upgraded), 291 - 293 fps

Again all on .25g BB’s

 
JinxDuh said:
Looking closer at the nub today, it seems uneven? 
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pic #3 looks to be off-centered

although that shouldn't be the cause of an fps variation, it's more a curving you're only going to notice on shooting.

 
Perhaps your aeg just doesn't like maple leaf bucking, barrel and chamber combination.  Also did you say your using a Macaron?  The XT barrel does work best with MR due to the larger window size.

As always your welcome to return any parts for a refund.

Did you get a chance to try the Macaron with an official nub?

 
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ak2m4 said:
Perhaps your aeg just doesn't like maple leaf bucking, barrel and chamber combination.  Also did you say your using a Macaron?  The XT barrel does work best with MR due to the larger window size.

As always your welcome to return any parts for a refund.

Did you get a chance to try the Macaron with an official nub?
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Yeah, using a macaron. The one I got has dots and a wave around it, the other ones I’ve had in the past have been smooth with 3 ridges. Maybe I’ve ordered the wrong rubber ?

I thought I had a spare omega nub but sadly I didn’t, so will get one ordered

JinxDuh said:
Yeah, using a macaron. The one I got has dots and a wave around it, the other ones I’ve had in the past have been smooth with 3 ridges. Maybe I’ve ordered the wrong rubber ?

I thought I had a spare omega nub but sadly I didn’t, so will get one ordered
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The pink/blue is what I have (But it’s yellow), and the yellow is what I’m used to getting. I assume they changed design or something?

View attachment 131629

View attachment 131630

 
That is just to differentiate the older macarons (3 stripes) from the newer super macarons (wavy pattern).

The main difference is the additional supports next to the contact patch and the patch being slightly wider/longer on the super variant.

 
From what you're saying you have a MR, that's the recommended bucking and the one I use to test.

However your hop chamber might prefer the Macaron version which uses a slightly smaller contact patch, it's all about trying different things.  it's worth just trimming the feet of the red nub a little or try the MR bucking with the stock nub. 

With the inner barrel and hop chamber outside of the gun apply the hop and look down into the barrel and see what the contact patch is doing, should give you an idea

 
I've used those ZCI blue buckings that come with their hop units before in similar circumstances when the gun seemed to be misbehaving with other 'fancy' buckings (maple leaf, unicorn etc) with good enough results.

 
The_Lord_Poncho said:
I've used those ZCI blue buckings that come with their hop units before in similar circumstances when the gun seemed to be misbehaving with other 'fancy' buckings (maple leaf, unicorn etc) with good enough results.
Click to expand...
I’m going to leave it as is for now, take it with me next month and see how it fairs. I have an omega nub ordered too just in case it’s still not great. The original set up was shooting up and to the far left, so it can’t be much worse ?

Put a standard black nub and bucking into my fathers E&L too and all of his issues stopped, no huge variations and no “no feeds” and double/triple etc feeds. Seems E&L’s just don’t like MR buckings or XT nubs. I plan on getting one of the Begadi rotary hops eventually so I’m assuming it’ll be a case of trial and error with that one too

 
I think for ak there's a vfc plastic rotary that's really good if you can find one, only about £15.  Maybe some AK owners can confirm this

 
Coincidentally I was trying to sort out a gun this morning that was shooting off to one side with a ZCI rotary and an Mr hop. After discounting the barrel being rotated to the side in the hop unit, swapping out the nub etc with no change, I realised something quite interesting. The hop arm on the ZCI unit had been poorly moulded. It appears moulded in two halves - and on my version, the two halves were not perfectly aligned. This resulted in a small step halfway across the 'cup' where the nub sits under the arm, therefore placing quite significant uneven pressure to the nub. 10 seconds of careful scraping with a blade sorted it, and now the gun is shooting dead straight. I've used ZCI units in most of my guns with good results, so this was a first for me. Had me scratching my head for a while!

 
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