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Tokyo Marui Mk23 - Magazine leak fix

27185 Views 23 Replies 7 Participants Last post by  RasyadArkan
Greetings ASF!

Lately I've been experiencing some leaks on my MK23 magazines. I decided to take photos and share how I've fixed them.

Basically, I have leaking mk23 magazines. I popped the pins out and drilled out the boss pin. Plugged the air pressure valve hole so I can use Green gas, and used silicone gasket in place of the rubber o rings.

Though I am no expert when it comes to airsoft gunsmithing or doing DIY work like most people here, I thought this might help those in the same situation.

Step by step:

Mk23 Magazines

Punch out the pins from where the boss pin is or what visually looks like the three pin side. The pins have knurling on the other side so you'd want to pop them from this side.

Once the pins have been removed, drill out the boss pin that keeps the bottom plate on the magazine. I used an old engraver bit since I felt I had more control with it.

After doing so you will be able to freely remove the bottom plate. Note that the spring from the air pressure release valve may fly out.

I applied epoxy on the air pressure release valve so that I may run Green gas. I let this sit for a few hours before applying silicone on the magazine.

Once this set, I tossed out the rubber O-ring and I applied the silicone gasket to the bottom plate.

I let it sit for a bit and then put them back together.
I let the magazine sit for a week before putting gas into them. So far they're holding and I haven't heard a hiss from them. This technique also did wonders to my leaking Kc02 long magazines.

I hope this helps! :tup:
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Thank you so much for this detailed guide! I just went through the exact steps that you did and now my once useless mag works great.

Rock on!
Sorry if this considered a necro, since it just a few months ago. Please tell me where i should post these if this was a necro. I've got some questions regarding alternatives of this method.

1. How deep the boss pin need to be drilled/engraved to remove it?
2. Can i use superglue/ca to substitute epoxy? Superglue is way cheaper ($1 vs. $10). For the record, i can even make my own concave nub (for vsr) using tissue+superglue so i guess it is strong enough to withstand green gas pressure inside it.
3. Similar as above, rtv silicone cost $20 in my country. Can silicone sealant which is used in aquarium replace it?

Silicone sealants "dilute" overtime with the silicone in your green gas, so it's better to use polyurethane sealant (such as the ones made for windshields) instead
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Thanks Dimitri. Do you know how to punch the 2 pin that doesnt need to be drilled? I can't even get those out lol.

The pins on one side have a knurled end to help it stay in body, if you lightly tap the pin with a pin punch and hammer, one way should move a little, that should be the right direction, but it is a game of try it and see
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So we push it to its exit by force from 3 pins mag side to 2 pins mag side? Can i just use allen keys instead of pin puncher? I'm afraid its on the expensive side of equipment in my town :( also, there are cheap engraver called Engraver EZ which cost only $2. Is it hard enough to dremmel the boss pin out?

Thanks a lot Handyguy, any help is appreciated.
Don't try an Allen key as that can slip, better to use a nail, just file the the point off first, I used my dremmel with a very small drill bit, 1/16 th or 1.5 mm then use a larger bit the same size as the boss pin, the mag wall is thin so you only need to drill an 1/8 th or 2.5 mm deep and then the base should pull out. I have done 2 of my mags today and filled the gas relief valve as the original thread said. I will update tomorrow once I reassemble the mag, I am using blue gasket goo to seal it, I will see how they hold after a couple of days of drying time
Basically use flat-filed nail and hammer to remove 2 pins on far end, and use dremmel or other drill equipment which has similar diameter to remove boss pin? And also is the gasket needed or could the O-ring just be relubed?

Thanks again, gonna wait for your post tomorrow.
The oring can be re-lubed and should work fine... but it's prone to recurrent leaks. That's why replacing it with gasket is a good idea.
So an update on my mag fixes, I followed the OPs directions, I used JB weld to fill valve holes, I left the seal in the mag but applied the blue gasket gunge over it and reassembled the mags, I left the mags for 12 hrs and today I filled them with gas and 10 hrs later still holding with no leaks. One thing I doon any seal or oring is to use silicon grease that is designed for aqualung assemble as it causes the seal/ oring to swell very slightly and makes a better seal. I now have 3 more mags in my arsenal. Thank you Spartan
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Nice update! Been waiting for you Handyguy. So you combine both silicone gasket and the O-ring? I'm gonna do it but currently waiting for my mini dremel that has yet to come :shrug:
Yes I left the original oring in place and just put loads of gasket goo around and then put the base back on , inserted pins, wiped off any excess gasket and then left them to dry, when I put some gas in I only put a small amount just to test the seal and when that held for an hour or so I then filled the mag as usual
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I've done this hundreds of times on every mag you can imagine (pistols, those crappy WE gen 1 AR mags, M700 mags, even custom made gas reservoirs for custom made RPK GBB drum mags, etc) and the best route is always to remove the oring / seals and just seal with the gasket maker. Otherwise the orings can still fail over time. Learned that the hard way.
Hmm will see how long the seals last and then next time not use the oring.
I followed this guide a few years back when I first got my MK23. (or was it the other one??) Either way, after 3 years mine are leaking. (Well just the TM one, the others have not, Y&P.)

I think I will try the polyurethane instead this time around.
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I have some y&p mags that are leaking, while using duster, but there is no circle showing where the boss pin is like on the tm mags. Does anyone know if the boss pin is in the same location? I am running duster because I have an extended barrel and want to keep it under 350 fps
The Y&P mags don't have a boss pin, mine does not , but it is a new one I have had for about 6 months, maybe older versions did, but mine started to leave so I did the gasket fix as per OP and it's fine now but it was difficult getting the pins in properly, I had to put a lot of pressure on the base plate so the holes for the pins lined up
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The Y&P mags don't have a boss pin, mine does not , but it is a new one I have had for about 6 months, maybe older versions did, but mine started to leave so I did the gasket fix as per OP and it's fine now but it was difficult getting the pins in properly, I had to put a lot of pressure on the base plate so the holes for the pins lined up
Thanks I got them open and the gasket sealed, and noticed there is no pressure relief valve to seal, so will these mags be able to take green gas if I go to a field with higher limits?
I only use green gas and and out of 12 mags only three have developed a leak over 6 months use and that could be from dropping them, any way it's an easy fix
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