hicapa 5.1 - cycle issues

[CJay]

hey guys so i have a TM hicapa 5.1 - I'm the original owner of the gun and it worked well for 2 years after a metal slide upgrade - everything else stock.

the issue I'm having is this:

gun started to half cycle sometimes and the problem eventually got worse. I'm now stuck with a gun that give crappy blowback and low fps on propane. I have replaced the following to no effect:

hop assembly, hop rubber, inner barrel outer barrel, nozzle (twice), piston head, piston cage and mounting, hammer, hammer sears, disconnector, valve knocker disconnect, leaf spring set trigger and trigge stirrup.

only 2 things not replaced are valve knocker itself and the full metal mid frame.

my question is this - has anyone ever had this issue and was i dumb and it was simply a worn valve knocker? valve knocker actually looks reasonable good :S

I'm 6 months into this repair and not a noob to airsoft gun repairs - done plenty of hicapa's but this one is starting to piss me off - especially since this in my own gun!!!!

EDIT:

and this hapens with both slidesets i have and all 10 mags - the 2 slidesets work perfectly on my buddies lower so i doubt it's a slideset issue or anything internally there

[Styrak]

Haven't look at/changed the nozzle valve?

However I'm thinking it might be a worn mag catch as you said it works on your buddy's lower just fine. Swap out just the mag catch and see if it works properly again. If the mag catch is worn and the mags are sitting too low, they won't make a good seal with the nozzle.

[CJay]

unfortunately already triwd with 2 mag catches sorry - forgot to mention it - even tried firing pushing the mags up higher

[Styrak]

Hm, maybe you have to look at that valve knocker and spring then! They're made out of crappy metal after all.
They always go on Sig pistols, not sure about Hicapa.

[CJay]

I have one on order lol. It's really the only thing I can think of being bad now



Looks a little flat on the contact area

[LongStone]

had the same "1/2 cycle" issue with mine
slide would not retract enough to load a new BB or bring the hammer past 1/2 cock

I replaced my piston head with a 9ball and a POM nozzle, solved the issue with my WE mags
still had issues with the 2 KJ-05 mags I have, finally pulled the valves on those and the felt like someone had poured sand in them, no surprise they weren't giving enough gas to cycle properly. Tried to clean and relube them a few times but they got back to "gravelly" within 1/2 mag. new valves on order.

[ILLusion]

That valve knocker looks 100% normal. That flat spot is suppose to be there. It comes from the mould like that to allow clearance of the valve when you insert the magazine with the hammer down.

The most common causes that I've seen with this symptom are:

1) Long aftermarket valve knocker (not an issue with yours, as yours is stock)
2) Cracked loading nozzle
3) Missing/damaged floating valve assembly
4) Interface issue between the metal slide and outer barrel.

What brand slide and barrel are you using? With aftermarket products, I've seen this happen with Guarder and Shooters Design.