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M4S Rear Sight Holder Issue


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#1 Doctor Kajita

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Posted 24 June 2008 - 08:40 AM

I'm posting this more because I'm displeased with the quality of the way the rear sight holder pin is designed.  I'm not sure there is a solution to this.

So, here goes.  As you know, the iron sights on the M4S fold down.  The front sight folds down and is locked in place by a button mechanism, very nice.  However, the rear sight is held down with a U-Pin, which has tension via a spring, which is located inside the rear sight assembly.  The spring has a little hook at the end (left side) that goes into a hole in the U-Pin.  But the hook is tiny, maybe 1mm long, while the hole in the U-Pin is 3 - 3.5mm (don't quote me on these measurements but you get the point).  This obviously makes it easy for the U-Pin to slide out of place and therefore the rear sight cannot properly be held down.

I asked KWA to send me a replacement spring in hopes that maybe the one on the gun is defective or damaged.  Nope, they look exactly the same.  I tried my best to get it to work but something isn't right as there's no conceivable way the U-Pin will be held in place with that little spring in normal game use.

That being said, I do appreciate KWA's responsiveness to sending me a replacement spring (and U-Pin), but I think this might be a design flaw.

Correct me if I'm wrong.

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#2 Guest_Radix_*

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Posted 24 June 2008 - 02:20 PM

You are absolutely correct and we are currently looking into the design. Thank you for your feedback.  :)

#3 Guest_allizard_*

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Posted 24 June 2008 - 07:54 PM

FYI, this is universal problem with this type of flip sight.  I lost the J hook on my CA gun before.  Same thing happen to a friend's flip sight.  And that happened many years ago and made by King Arms.

#4 Doctor Kajita

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Posted 24 June 2008 - 08:05 PM

I think since the rear sight has a big spring that holds it up, there is no need for the latch (what I called the U-Pin) to have any tension.  A simple pin through a hole on the other side would keep it from falling out.  Maybe this was a little over thought in its design?  Or, is that how the real steel version is like?

#5 Guest_allizard_*

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Posted 27 June 2008 - 10:35 PM

can't answer that.  haven't seen real steel version.  I just remember couple years ago A&K also make an M4 S-system.  Also have similar problem with rear sight.  I wonder if it happens on Marui too.

#6 Doctor Kajita

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Posted 08 July 2008 - 08:47 AM

View PostRadix, on Jun 24 2008, 03:20 PM, said:

You are absolutely correct and we are currently looking into the design. Thank you for your feedback.  :)

I'm not going to hold my breath but when do you think KWA might have some sort of resolution to this issue?  I kinda want to use my iron sights in some games and I also want to use my scope for some.  I don't want to have to take off the sight every time I decide to use my scope as it's easier to lose parts that way.

#7 Guest_Radix_*

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Posted 08 July 2008 - 09:57 AM

View PostDoctorKajita, on Jul 8 2008, 09:47 AM, said:

I'm not going to hold my breath but when do you think KWA might have some sort of resolution to this issue?  I kinda want to use my iron sights in some games and I also want to use my scope for some.  I don't want to have to take off the sight every time I decide to use my scope as it's easier to lose parts that way.

I can't give you a exact time frame but I can confirm that it's on our list of design reviews.  Meanwhile you can try this quick fix by tightening the tension of the spring so the pin will stay put.   First, remove the rear sight from the rails.  Pull the "J" pin out slightly, not completely but just enough so you can rotate it free of obstruction from the base. Rotate the pin one to two extra revolutions or enough so you feel a heavy tension in the rotation. Push the pin back into it's original resting position.  When there is enough tension, the pin will stay in it's place.

#8 Doctor Kajita

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Posted 08 July 2008 - 09:49 PM

View PostRadix, on Jul 8 2008, 10:57 AM, said:

I can't give you a exact time frame but I can confirm that it's on our list of design reviews.  Meanwhile you can try this quick fix by tightening the tension of the spring so the pin will stay put.   First, remove the rear sight from the rails.  Pull the "J" pin out slightly, not completely but just enough so you can rotate it free of obstruction from the base. Rotate the pin one to two extra revolutions or enough so you feel a heavy tension in the rotation. Push the pin back into it's original resting position.  When there is enough tension, the pin will stay in it's place.

Sweet!  That did it for me!




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