PolarStar Jack pkm issues

[VIV]

I don't know if this is the right place or if anyone can help. But since I got my polar star I've had nothing but issues, I've got it installed in a pkm and on the first day which I was able to use it I had an issue where none of the bbs would shoot for a while and then they would all shoot out of the barrel at once, I've switched to a higher quality bb and no longer had that issue to find the air hose that connects to the back of the unit was coming loose meaning I wasnt able to use it. Now after taking it home and tightening the connector I know have the exact same issue and I'm also finding shattered bbs. Would anyone know what might be causing this? If it helps I'm using the standard barrel which came with the gun which I have rhopped, and a prometheus hop up rubber. 

 

[Adolf Hamster]

possibly the rate of fire is higher than the magazine feed allows, so she's trying to chop a bb that's half fed into the chamber.

what kind of settings are you running at the minute?

 

[sjhirst]

I'm probably stating the obvious, but make sure your nozzle alignment is spot on, Also do the BB drop test on the  hop up rubber- do they drop through the hop and barrel easily or take a bit of force?   have a quick look at this YT vid : https://www.youtube.com/watch?v=156t4FrN2KA

 

[VIV]

Not sure if this is how im meant to reply to posts very new here @Adolf Hamster when I had it working I had a nozzle dwell of 50 something and a fire rate of around 30 but unfortunately whilst trying to get it chronod the ref dropped the gun on the FCU smashing the screen meaning that only half the screen works which has made it a bit difficult to change the settings since. im on the lookout for another so if you know of somewhere that has polar star FCUs in stock it would be greatly appreciated. 

@sjhirst thanks for the link to the video that was really good to know, I performed all of those tests and the only one which I think may be an issue is the one where you see how much force is needed to go down the barrel. using an Alan key it seemed like not to much force but difficult to say I don't know if this will make any sense at all or even be remotely helpful but trying to blow a bb through the barrel with my lungs was pretty much impossible, but I don't know how much force it should really take or if thats a normal thing 

 

[Adolf Hamster]

Not sure if this is how im meant to reply to posts very new here @Adolf Hamster when I had it working I had a nozzle dwell of 50 something and a fire rate of around 30 but unfortunately whilst trying to get it chronod the ref dropped the gun on the FCU smashing the screen meaning that only half the screen works which has made it a bit difficult to change the settings since. im on the lookout for another so if you know of somewhere that has polar star FCUs in stock it would be greatly appreciated. 

doesn't sound too extreme then, you could try dropping the rf a bit just to see, what pressure are you running her at? i'd imagine she might need to be quite low for a barrel that long.

can't help you with the fcu, funny mine's the same but it's still usable, i mostly program for accuracy rather than out and out rof anyway. you can do the ol' drop her to 1 then count up to set it then check with the rof on the chrono.

just throwing it out there just in case, but you don't have a suppressor or anything like that on her? pretty common to chop bb's if they're clipping the end coming out.

 

[VIV]

doesn't sound too extreme then, you could try dropping the rf a bit just to see, what pressure are you running her at? i'd imagine she might need to be quite low for a barrel that long.

can't help you with the fcu, funny mine's the same but it's still usable, i mostly program for accuracy rather than out and out rof anyway. you can do the ol' drop her to 1 then count up to set it then check with the rof on the chrono.

just throwing it out there just in case, but you don't have a suppressor or anything like that on her? pretty common to chop bb's if they're clipping the end coming out.

At the moment I don't have anything on the end of the barrel apart from the mock flash hider which came with it. Im waiting on a chromo to arrive so I might hold of on doing to many tests until it does so I can set it up fully and not waste too much air. I'm also going to try to get a new hop up and run it at a lower pressure its set around 100 psi at the moment 

 

[Ajcorb]

I had a polar, fully home made and i had no bbs feeding to start with. the nozzle was for an M16, and not for the M4.  i hear you say they are the same internals... appently not. the M4 carbine has shorter nozzle.  (we' are talking 0.something of a mm) i change that and then had no issues. even running a 600mm barrel with 30rps no issues at all. 

Feeding can be a problem as that speed,  i found the only mags that could feed fast enough where the speed Lonex ones ( 450 rounds with the pull cord winder) never had issues with them. 

 

[Adolf Hamster]

I had a polar, fully home made and i had no bbs feeding to start with. the nozzle was for an M16, and not for the M4.  i hear you say they are the same internals... appently not. the M4 carbine has shorter nozzle.  (we' are talking 0.something of a mm) i change that and then had no issues. even running a 600mm barrel with 30rps no issues at all. 

Feeding can be a problem as that speed,  i found the only mags that could feed fast enough where the speed Lonex ones ( 450 rounds with the pull cord winder) never had issues with them. 

the jack especially tends to be nozzle sensitive due to being open bolt, and you're right about the mags try to push beyond 40 ish rps and most midcaps will start to misfeed. of course tbh you don't really need to push it that fast beyond pre-game showboating.

i have been fighting with mine of late, she seems to struggle to feed reliably (especially on a full mag) at around 75psi which sadly is also right where she needed to be for our 1j limit and my barrel length. i have been trying a few things but not really good long term solutions. there really needs to be a low-flow nozzle for these things (similar to the fusion/f2). might have to just shorten the barrel a bit more as a workaround.

the problem with the jack is it's an entirely pressure fed system, the likes of the fusion/f2 just need enough air to overcome their springs whereas the jack needs air to extend and retract the nozzle.

 

[VIV]

Bit of an update for anyone whose interested, since my last message i got some new tools and a chrono to help me out a bit and have been slowly increasing its performance. and working on it with the biggest struggle being not being able to refill my hpa tank and not having anywhere to properly shoot it as my garden is way to public for that. fixed the first issue in the end by tightening the air hose that goes to the unit and redoing my flat hop mod. now i end up taking it with me to skirmish sites to fill up my tank and test it and since my last message ive also had to replace the magazine insert and clean the o-rings inside the unit. unfortunately meaning i am still yet to use it in a skirmish. in all honesty though i do enjoy tinkering away at things like this but hope i will be able to use it in my next skirmish where i have access to a hpa pump. 

 

[Adolf Hamster]

i feel you man, the endless search for compressed air is the less fun side of hpa ownership.

what about grabbing a dive tank? you'll need to get it re-certified every few years but a good fill from a dive shop will see you filling half a dozen times into the smaller tank.