KSC Mk23 SOCOM only shoots a bb every other shot

[kdogg]

I have a question for you guys. I have a KSC Mk23 SOCOM sitting here and its got an odd problem.

The gun will only fire every other round. Every time I pull the trigger, the gun goes off and the slide cycles but it only fires a BB every other shot.

For example it it goes "pop" bb shoots, "pop" no bb, "pop" bb shoots, "pop" no bb, etc... Slide always cycles it just only fires a BB every other time.

This is consistant too, it only shoots a BB every other try.

I'm thinking somethings broken but I don't know what part to look at.

Anyone see this issue? Anyone know what part crapped out?

Thank you.

[PTE. Pyle]

first off please fill in your profile properly.

now have you tried puting some sillicone oil on the follower? (the little black peice that pushes the bbs in to the gun)

[Ghost Snake]

Does it always fire every other time, all the time? Or does it fire 2 in row, or skip 2 in a row sometimes?

[kdogg]

Ok I just noticed something. The slide only cycles a tad bit on the shots when there is a round in the chamber.

It's like the guns doing this, when there is a BB chambered, all the gas power goes down the barrel and hardly any is used to cycle the slide properly. This would explain the dry fires with no BB and only the slide cycling.

It's as though if there is a BB chambers, the gas is used to push the BB out but hardly any is used to cycle the slide properly. If there is no BB in the chamber, the slide gets plenty of gas to cycle. Seem to be affected by that small spring loaded nozzle being pushed back or not. Almost as if the thing that divert the gas flow isn't working right.

[Shinjin_MC]

yep
sounds like its that spring loaded nozzle
if the spring in there is not strong enough it results in what you are experiencing
chamber 2 or 3 bb's and fire
if it shoots then it definitely the nozzle

[Greylocks]

Second request; fill your profile properly. 'Earth' is not a good location for us to find you expert local help.

What method do you use to fill up with gas? Be precise, that may be a cause of your problem. Read about GBB guns in the FAQ section.

[MadMax]

I suspect that the firing pin lockup may be malfunctioning. There is a feature in nearly every GBB which locks the firing pin forward until the slide recoils about 1/3, even though the hammer is recocked in the first 5-10mm of travel. This leaves the nozzle body still charged with pressure until the piston clears the nozzle and vents the nozzle.

KSC uses a floating valve in the nozzle body which pops forward when breech pressure drops.

With no firing pin lockup, a breeched pellet maintains a high pressure in the breech until it leaves the barrel. The floating valve pops forward closing the breech passage and diverting gas to the recoil internals. If your firing pin lockup isn't working, there isn't much gas pressure left when the hammer is recocked and is pulled off the firing pin.

With no pellet breeched, the floating valve should pop forward immediately and put your gun into recoil mode which might fully cycle the slide.

http://tech.airsoftcanada.com/KSC/mk23_install_1.gif

I'm guessing that #64 is the firing pin and #69 and #73 are somehow related to the lockup feature. I haven't taken apart a KSC USP before so I can only infer from the dwg. Look for a moving part in the top of the frame which gets pushed down by a surface on the underside of the slide about 1/3 to 1/2 of the way back. It's probably related to the firing pin lockup feature.

You can diagnose a firing pin lockup problem my dryfiring your frame with the slide removed. Ease the hammer down with your thumb instead of letting it slam forward. Some GBBs can damage themselves if you dryfire with no slide mounted (Glocks). Look down the magwell for the firing pin which should stay pushed out even while recocking the hammer. Push down on a movable bit at the top of the slide to see if it unlocks the firing pin and allows it to snap back.

[Ghillie973]

I have the same problem in my KSC G19. I pretty sure my problem is caused by the two springs that keep the nozzel back (part #23). I'm just waiting on the parts.

Try Shinjin_MC's advice and check the spring in the nozzel.

[MadMax]

Funny thing as that those nozzle return springs aren't actually critical. You can remove them and a GBB will operate properly. The only thing they do is tuck the nozzle body away when the slide is locked open on an empty mag.

I think Shinjit is referring to the floating valve spring INSIDE the metal body. If the spring is too lax, the GBB would switch to recoil mode prematurely or the valve wouldn't close the breech passage completely resulting in a weak recoil.

[Shinjin_MC]

yep, the two springs that pull the actual breech back dont do anything
its the one that is actually in the nozzle assembly itself
when you lock the slide back its that nozzle that you see, if you push it back and forth with your finger it should spring back very quickly
sometimes the return is "mushy" and thats where the problem is
I had an MK23 2k5 version that did exactly that

filling gas wouldnt really be an issue because if he filled it wrong, it would spray him and give his fingers frostbite or something, but not the consistantly funky blowback operation

[kdogg]

Sorry I wasn't sure which piece of info in my profile you guys were talking about. I see so many other people with odd ball placed listed in there profiles I didn't think a real response was needed.

Ok, back to the Mk23 issue.

Yes this gun uses the spring loaded nozzle.

The gun doesn't load 2 and 3 bb's at all. What happens is if the guns not chambered, no bb, it cycles, dry fires, whatever you prefer to call it fine. If a BB is in the chamber and the spring nozzle is pushed back the bb's does kind of shoot out but the slide doesn't cycle at all most of the time and the rare times it does, its not enough to push it back far enough to chamber the next bb.

I agree, something inside where the nozzle, piston cup, seals, etc are located is broken I just didn't know what part could cause such a problem.

[Shinjin_MC]

oh, I meant, manually chamber those 2-3 bb's and squeeze the trigger
if it shoots, that nozzle spring needs to be changed

are you using duster? or propane?
I found with duster it would act another kind of funky

[kdogg]

I have to ask why would manually chambering 2 or 3 bb's and having it fire tells me anything?

If the guns working properly, shouldnt anything in the chamber shoot out, no matter how many?

I have tried actual cans of 134A, Green Gas and Propane in this gun.

[aaronvince]

was this problem ever fixed?