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[Sticky] Dboys K98 Gas Bolt Take Down Guide

 
(@rammix)
Prominent Member

Hi,
I thought I would put together a K98 Gas bolt take down guide as mine was venting gas out of the safety lever area and there wasn't a picture guide anywhere on the internet to show the internals

first remove the bolt from the K98

remove the back of the safety using the small grub screw (no need to take this out but wanted to see what it was like inside)

remove the small screw that holds the whole back piece onto the bolt

remove the 2 valves that sit on top of the bolt remembering which hole they screw into

remove the 2 small grub screws either side of the bolt, these are 2 different sizes so use the appropriate keys

if you look down the end of the bolt you will see the gas chamber as I call it, you will also see that its threaded, you will need a bolt with the same thread to extract the gas chamber, just screw the bolt in, not too tight, then pull carefully and slowly until the gas chamber has come out. Its a very tight fit, but once it starts to move it will come out fast!

another picture where you can just see the plunger that the firing pin pushes into

all the parts laid out

the problem I had was that the rear O rings on the plunger were a bit of a slack fit, I then put them in car brake fluid for 15 mins (not too long or it can bugger em up) unsure what sizes they are or where to get replacements :?

all that needs doing now is to reassemble the bolt in reverse and test





the bolt on mine after a 10 secs fill of Abbey predator Ultra gas managed 25 bolt cycles at room temperature with no leaks at all
Just need to take it up our club now and put it on the crono, also working out how to make a shell catcher for it

Thanks for looking, any feedback would be great :D

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Topic starter Posted : 16/03/2011 10:05 pm
flatrajectory
(@flatrajectory)
Estimable Member

Excellent takedown review Rob, cracking photos too.
Great job on the woodwork too.

pete.

"REMEMBER, LIFE IS NOT A REHEARSAL"

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Posted : 19/03/2011 7:38 pm
(@rammix)
Prominent Member

cheers

accuracy is pretty good :) , thanks to Pete (flatrajectory) with some pointers on how to rebuild the hop up :D need to give it a full test once I get up to our airsoft site

the stock was sanded back to bare wood then given one coat of colron american walnut wood dye and 3 coats of parker hale express gun oil
all metal work was rubbed down and Phillips professional cold blue applied

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Topic starter Posted : 19/03/2011 10:53 pm
(@jimmiroquai)
Estimable Member

Nice! What velocity does it shoot at?

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Posted : 20/03/2011 12:21 am
(@rammix)
Prominent Member

unsure as yet, need to get it on a crono will be a couple of weeks before I can get up our site

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Topic starter Posted : 20/03/2011 12:27 am
(@rammix)
Prominent Member

The K98 had its first outing last week Im very very happy with it! accuracy got better as the hop bedded in, damn crono was playin up so we couldnt get an accurate reading we estimated it to be around 480fps to anything around 520fps, also managed to get 6 clipper strips (30 shells) before it needed a refill as well, so not bad overall! still need to work on a shell catcher of some sort :P but was great fun to use

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Topic starter Posted : 23/04/2011 10:18 am
JD7
 JD7
(@jd7)
Illustrious Member

Result

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Posted : 23/04/2011 11:51 am
(@rammix)
Prominent Member

No Problem fella, just take your time and you should be ok, any questions just ask

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Topic starter Posted : 16/06/2012 1:26 pm
(@rammix)
Prominent Member

sent you a pm

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Topic starter Posted : 04/08/2012 11:12 pm
CHThree
(@chthree)
Noble Member

Don't soak them in silicon oil, it won't do any good. You need to soak them for a short while (rammix suggested 15 mins) in car / motorcycle brake fluid. This tends to restore most rubber o-rings. Be careful of the break fluid, it will damage any painted surfaces it gets on.



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Posted : 19/09/2012 4:03 pm
TheChef
(@thechef)
Honorable Member

Hi guys

I've got a strange problem with my Dboys K98 and wondered if you had experienced it or know what the problem is ? The rifle fires okay then suddenly won't fire, it cocks and clicks when you pull the trigger but no gas is released. If I then vent all the gas off and refill its okay. This seems to be happening every 5-15 shots at the moment, it was previously okay.

Any ideas?

Cheers
Russell

German

Russian

British

Japanese

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Posted : 20/07/2013 1:51 pm
(@rammix)
Prominent Member

mav0016

might be worth stripping the bolt down again and checking, I didn't notice an O ring at the front when I did mine, I have another one to do in a few weeks so will have a look

theChef

only advice here I could give is to strip the bolt down, check all O rings, lube and put back together, sounds like its a gas pressure issue, when the pressure drops after firing each round the firing pin as I call it is sticking

hope this helps chaps

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Topic starter Posted : 22/07/2013 11:18 am
TheChef
(@thechef)
Honorable Member

theChef
only advice here I could give is to strip the bolt down, check all O rings, lube and put back together, sounds like its a gas pressure issue, when the pressure drops after firing each round the firing pin as I call it is sticking

Hi,
Thanks for that, I'll try a strip down and see how it goes. I notice that in your pictures that the bolt fill valve appears to be towards the rear of the bolt and the vent screw is towards the front, mine is the other way around, do you know what difference it makes ? as you state "remembering which hole they screw into" in your take down guide.
Cheers

German

Russian

British

Japanese

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Posted : 22/07/2013 12:04 pm
 mec
(@mec)
Eminent Member

Hey guys, I had the same problem and fixed it but when I put it back together it leaks from the front, right out the tip. I put it back together the same, Is there an o-ring at the front or something?

I had the same problem, there is in fact an o-ring at the front between the piece rammix has the wrong way round in the pic and the bit that it drops into, I didn't notice mine till it fell out during disassembly

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Posted : 05/08/2013 4:26 pm
(@rammix)
Prominent Member

didnt notice the front O ring either, cheers for the heads up mec, hopefully should clear a few issues for other people as well :)

Hi the Chef, unsure what difference it would make with the valves, as mine was only venting from the back of the bolt I just dissembled it and put the valves back in the same holes

cheers
Rammix

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Topic starter Posted : 05/08/2013 8:26 pm
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