New Gun Niggle

[strykerles]

Recently purchased a CZ Bren A1 M95 (mosfet version)

fires lovely and everything works

problem is that if I only slightly pull the trigger in semi it will go full auto and occasionally will do a double tap on every trigger pull

Mosfet problem  or could it be something more simple?

thanks for looking

 

[DerDer]

Out of curiosity, what kind of battery are you using with it?

Have had double shots before on a beefy 11.1V in an aeg. 

 

[Adolf Hamster]

i wanna say it's as simple as the contacts are engaging before the trolley is far enough forward to get caught by the cutoff lever.

 

[strykerles]

Out of curiosity, what kind of battery are you using with it?

Have had double shots before on a beefy 11.1V in an aeg. 

11.1v 1200mah slim stick lipo as recommended. I'll try a 7.4 tomorrow and see if it still does it

 

[Sitting Duck]

i wanna say it's as simple as the contacts are engaging before the trolley is far enough forward to get caught by the cutoff lever.

Deffo sounds like a bit COL related

is this gun new ???

or s/hand with worn alloy COL ???

Sounds worn or mix/match of switch/trolley bits not operating 101% efficiently

some trolleys have a considerable longer/shorter copper contact lug/point

which as @Adolf Hamster said can make contact with switch "prongs" before COL can get a chance to pop the trolley

also a worn or low rising COL on a high trigger sear will pop late or sometimes struggle to pop trolley

now run it on 11.1v where you are into say 20+ on std motor, worn/poor switch/COL efficiency

then yeah you are going to get some funny weird results when gun doing shit you don't expect

if it is new - that is crap

if s/hand then COL/trolley parts need a little investigation to resolve this issue I reckon

deffo prongs/trolley are making contact before trolley/COL can pop

and perhaps struggling to pop quickly/efficiently other times from worn COL and/or high sear

I mean yeah you can be getting overspin @ 30rps

but as it isn't popping on slight trigger pull on semi points to what AH said

V3 box ???

looks like std g36 selector type plate, reg SHS v3 COL, v3 switch etc...

but somehow wear or incompatibility/efficiency issue has come into effect in operation

hence me asking is gun new or s/hand ???

(& rof you are seeing etc...)

but wanked trolley/COL looks likely if you want to run it with some snap

 

[strykerles]

@Sitting Duck

The gun is new, all I've done is change the hop rubber and nub. 

The gun is a v3 box with an ambi fire selector

As I said, if I do a full trigger pull its fine. 

If I only.half pull the trigger it fires full auto or sets semi to 2 round burst 

 

[Sitting Duck]

@Sitting Duck

The gun is new, all I've done is change the hop rubber and nub. 

The gun is a v3 box with an ambi fire selector

As I said, if I do a full trigger pull its fine. 

If I only.half pull the trigger it fires full auto or sets semi to 2 round burst 

bit of a bummer, get used to pulling trigger fully I guess

switch has long prongs, trolley engages (just) before COL can properly get under it as AH said

fine tuning the triger/trolley/COL bollox is a PITA

So stuff is just generally slapped in with a bit of a margin to operate....

Sometimes a different trigger jumps off trolley at full pull

sometimes the trolley engages a bit early - fine for normal operation

(but fine pull then you notice it - like in your case)

sometimes the COL wears or not compatible & you get issues

even replacement selector plates can cause issues - yet most of time it works within a margin

bit of a PITA it is a bit picky on a new gun, normally without a mosfet

the lug would burn down a bit over time - this won't be so with the mosfet

so it will be something you need to get used to if you keep the gun

and maybe investigate when it needs a bit of a service at some point

meantime get used to pulling the trigger fully I guess

you could run it on 7.4v = slower and will reduce the cycle time so gun/col catches on trolley better

(as you pull the trigger more fully at slower speeds)

but guess on snappier 11.1v you just need to pull the trigger more assertively I guess so it catches & pops the trolley

 

[strykerles]

I really like the gun so I think ill keep it and when it comes to service the gun. I may replace a few internals. 

Thanks for the help

 

[strykerles]

UPDATE!!

upon using a 7.4 lipo it no longer double fires and isn't as sensitive to a slight trigger pull