A Thread About Skara Questioning His Arp-9

[Skara]

Title's kinda self explanatory.

 

I was looking at my ARP-9 the other day, great little gun, nice trigger response, nice ROF (around 22 RPS in its stock configuration), compact size and somewhat lightweight.

 

But it has a few niggles, namely the hop chamber being a bit meh, the stock bushings being brass, the gearbox (as with all G&Gs) lacking a QC spring and having the screws on the other side and the magazines. Most of these cons aren't really an issue, bar the last one.

The available magazine really kill the gun's potential..

The stock high cap sucks, can't feed more than 10 bbs before needing winded again, needs to be bashed often (bbs get stuck inside because of the slim design) and the winding mechanism itself is crap.

The G&G midcaps are shit, €30+ per mag and they only hold 60 rounds. Absolutely impossible to find.

The Classic Army X-9 mags are about €25/30 per mag depending on the retailer, hold 120 bbs but 3 out of 3 mags that I have come with springs so weak they feed the first 10 bbs and then don't have enough tension to lift the other 100. Also really hard to find here.

Then there is the drum: that thing is marvelous, feeds everything, is rock solid and being mechanical it doesn't require extra batteries. Very little that can go wrong with it, props to G&G for making it good (also available in 5.56 form which I have, mp5 version and others).

Don't get me wrong, the gun + drum combo lets me run really lightweight loadouts (belt, small pack, that's it) which is fantastic for summer games, but sometimes I feel like I'm missing something by not having to reload.

 

So I'm here questioning the permanence of the ARP-9 in my "armory", ideally I should just buy some superfeed springs but, just like them magazines, they are hard to come by.

 

While browsing the internet I've come across a few neat looking PCCs, namely the KWA QRF series, specifically the MOD 1 with its curved MP5 style magazines.

The thing is way out of my league though, retailing at €350+, being out of stock everywhere and has the same issue of proprietary magazines.

 

Following that style, I have found the King Arms PDW 9mm series of AEGs. They take regular MP5 mags, opening up to a whole lot of different mags (high caps, midcaps and G&G drums) for much less than say G&G/CA/KWA mags. From what I've seen online they are mostly polymer, feature a weird 7mm QC gearbox and a somewhat basic mosfet, along with a supposedly decent 25k motor. Oddly enough they come with an older style gear hop unit.

Price wise, they aren't the cheapest, being mostly unavailable in Italy (can get some from the UK for roughly €210/220 posted).

A few variants available, the shorty with a 5" ish front end, the long that should be around 7/8", the M-Lok and the SD (M-Lok variant with a suppressor).

I'm particularly interested in the Long version, it has that MP5A5-esque look that is very intriguing, plus it's of decent length.

But I've heard mixed feelings about these guns, some say they're great, others say they're shit (as with all things really), some complain about the magazine wobble.

 

I don't care too much about the internals, if I end up buying one I'll be doing the same shit all over again (13:1, HT motor, good FCU, blah blah blah).

 

What should I do?

 

Halp pls 😢

[Steveocee]

ARP556??

 

Retains everything you like about the ARP9 but swaps out to the 5.56 platform. It is more or less the same gun.

G&G hopups are meh but can be swapped for a ZCI rotary to sort them cheaply.

 

FWIW I recently had a small surplus and was really interested in the ARP series, ended up with a CM16 SRS due to it being similar if not lighter than ARP556 and it costs a lot less. Yeha it has a 7" front end opposed to 5" but if I'm playing in areas that tight I'm on the pistol anyway.

[Skara]

Has to be pistol calibre though, I already have 2 (well one is still somewhere between Poland and Italy) tricked out M4s.

[Steveocee]

2 minutes ago, Skara said:

Has to be pistol calibre though, I already have 2 (well one is still somewhere between Poland and Italy) tricked out M4s.

 

Apologies, I completely missed that bit lol

 

Can't you just get a Primary adapter for glock to mp5 mags and run your AAP?

[Skara]

Unfortunately not an option, I'm keeping the AAP as a sidearm.

Plus running HPA here is tricky, I don't have a compressor, scuba shops aren't keen on filling HPA and I'd like to keep my scuba cylinders for diving

[ziCk_]

On 23/10/2020 at 13:14, Steveocee said:

Can't you just get a Primary adapter for glock to mp5 mags and run your AAP?

 

Getting one of these right now is next to impossible... ask me how I know :/

[Sitting Duck]

Feed problems - bet it is nozzle retraction

or part of the issue

 

Add delayer - but the CORRECT TYPE

 

there is a smidge of extra material that just fits over the sector's tappet cam

thus pulling the tappet back a whisker extra more

other delay clips are just shit by comparison...

if you only have a 5.5mm gap in front of the nozzle it will struggle to fee a 5.95mm BB

(no matter how long the tappet/nozzle is held back for

 

Some mags have a stronger spring and will attempt to force it through with enough force

but won't last 7 maybe why it only feeds 10 BB's if you are lucky

 

I've covered this before...

 

 

But the tappet/nozzle window on V2's is 1mm smaller than on V3's

so you really have to ensure the nozzle length is correct

21.38mm or a SHS Red should do @ 21.40mm if you use a delayer

(or make your own with a sleeve over cam)

 

SHS v2 tappets also retract a whisker more than most others

 

But check for bottoming out on cylinder head in top half of box

blah blah blah - said it loads of times

 

you can even go nutz on a red cylinder head...

see that ridge at the bottom, file it away (carefully after removing o-rings)

then mark cylinder and file a whisker of the cylinder itself - say 5 o'clock to 7 o'clock

clean up & reassemble...

Now you have an extra 0.5mm to 0.75mm extra retraction space on tappet plate

 

Again - check tappet plate bottoming out on cylinder head at full retraction

you can gain nearly 1mm more nozzle retraction

 

BUT pay attention as the sector rotates in top half of box as it goes to draw back the tappet fin

just before it engages the fin you may feel some resistance...

this is a large delayer or sleeve hitting the underside of tappet plate - JUST BEFORE it engages the fin

It is a really tiny area of contact, so on the area just in front of the fin, you may need to lightly file away

some material - not a lot a real fine shave

an area right in front of fin to say 5mm in front, only needing to file off say 0.25m to 0.5mm in most cases

 

All the checking should be done in the TOP HALF of the box

the lower half just wobbles way too much

so this checking of tappet retraction MUST be done in top half

(which is handy coz all the wiring & shims & crap stays in lower half)

so it is a pretty easy thing to check the sector delay tappet cylinder etc.. - all retracting as much as possible

without it bottoming out on cylinder head or bumping underneath the tappet plate itself

 

V2's are a wank, not all V2's need the tappet plate filed underneath, but if going nutz for max retraction

then it is quite common if taking the piss on tappet retraction

 

V3's seem to be more forgiving and retract more by default than v2's

 

**** SLIGHT WARNING **** 

 

If you have a v2 and are REALLY taking the piss, filing cylinder head & cylinder

massive sleeve to REALLY retract tappet, requiring the underside of tappet shaved

 

ON A CONVENTIONAL TRIGGER/TROLLEY SWITCH - one thing to watch out for if taking the piss

 

At FULL TRIGGER PULL, ramming the trolley home, the extra tappet retraction

could damage the tiny nipple/lug on top of trolley where the trolley spring sits

 

it is supposed to just miss by that groove in the tappet plate underside

Sooooooo - if you are REALLY taking the piss on tappet retraction

you need to extend that trolley channel or groove on the underside

to avoid the trolley spring lug hitting the end of the groove and breaking that nipple clean off

(painful), but I had it happen once & so the channel gets modded/extended to prevent this

 

It is something that will only happen on CONVENTIONAL TRIGGER if TAKING THE PISS

now on the ARP9 think that is ETU so no trolley to tear off

so no need to worry about extending the trolley channel on the underside of tappet plate

 

ANYWAY - TL-DR crap as per usual...

 

you need to ensure the nozzle length is correct, maybe sand the front to help seal a smidge

(doesn't help feeding at all)

then try to go for max possible tappet retraction - the delay DURATION matters little if retraction is small/worn

add delayer/sleeve, check for contact/wear/rubbing blah blah blah to the power of 10 etc...

 

Hopefully you end up with an extra 0.5mm to 1mm extra retraction

that will assist feeding even on the shittiest of mags at a moderate snappy rate

 

if you still got feeding issues then the nozzle is too long, hop rubber bucking lips too tight

or the mags are really fucked (no spring tension at all)

But you would have the ability to deduce or work out the main cause by power of elimination

 

But tappet retraction or nozzle space to feed a bb won't be an issue any more

you look into some of this crap and I assure you, your gun will feed better on almost mag

 

it is them poxy v2's, the tolerance on tappet window is quite fine, bit of wear on fin

not a great amount of retraction to begin with and you get feed issues on some mags

Some mags might just shift the hop unit slightly forward say 0.4mm and feed like a dream

 

of course you could shove a thin o-ring or something in front of hop between box/hop

pushing the hop forward and it should feed better - but gain a slight blowing at lips

so fps drops a bit - but should feed better, shifting hop forward nearly half a mil

 

mega TL-DR - just check tappet retraction in top half of box & look to improve with clip/sleeve etc...

[Adolf Hamster]

It sounds like someone's looking for an excuse to buy a pp19....

 

Or an mp5, if you think of it as a g3 pcc......

 

Or a p90, if you think of it as an f2000 pcc.....

 

Fuck it whichever one you go for buy me one too

 

[Skara]

2 minutes ago, Adolf Hamster said:

It sounds like someone's looking for an excuse to buy a [insert_gun_name_here]

Could be.

 

Maybe it's just me being fed up with proprietary stuff.

And wanting a less common base to build a wanker gun onto

 

The more I look at it, the more I want it.

[Skara]

I'm so bad at not buying stuff -.-

 

Just bought the KA PDW (shorty version in grey).

 

More technical question incoming, how would you build something that has lightning fast cycle time in semi auto, but actually slow (low 20s) ROF?

[Adolf Hamster]

4 minutes ago, Skara said:

More technical question incoming, how would you build something that has lightning fast cycle time in semi auto, but actually slow (low 20s) ROF?

 

hpa

[DerDer]

25 minutes ago, Skara said:

I'm so bad at not buying stuff -.-

 

Just bought the KA PDW (shorty version in grey).

 

More technical question incoming, how would you build something that has lightning fast cycle time in semi auto, but actually slow (low 20s) ROF?

Beefy 11.1V Lipo and bring the RPS down with a suitable Mosfet that had ROF control. 

 

[Skara]

On a fully charged 11.1 the response is quite meh, I believe the motor is weak and there's a huge ass spring in there to get the 1J output.

 

The stock ROF isn't too bad, in the low 20s I think, will get more accurate readings this weekend.

 

Not going for anything extreme this time, just some 16:1s and either a SHS HT or something like 22tpa to balance things out. This thing will be spammed in binary on a 11.1 anyway to make people cry when I play cqb (once in a blue moon)

[Lollingsgrad]

On 11/11/2020 at 16:47, Skara said:

More technical question incoming, how would you build something that has lightning fast cycle time in semi auto, but actually slow (low 20s) ROF?

 

For nice trigger response but sensible ROF I would suggest standard 18:1 gearing, 11.1V lipo, optical MOSFET with precocking. I like the Perun one in my AK74SU. Does about 22 RPS but retains a snappy semi aided by a short light trigger pull.

[Skara]

7 hours ago, Lollingsgrad said:

 

For nice trigger response but sensible ROF I would suggest standard 18:1 gearing, 11.1V lipo, optical MOSFET with precocking. I like the Perun one in my AK74SU. Does about 22 RPS but retains a snappy semi aided by a short light trigger pull.

It's my plan (although using the ETU upgrade kit instead of the optical).

The only problem I see is the motor, the stock one is really weak.

[Sitting Duck]

2 hours ago, Skara said:

It's my plan (although using the ETU upgrade kit instead of the optical).

The only problem I see is the motor, the stock one is really weak.

 

How's that advanced SLE dooberry in ya gun....

 

http://kwa.com.hk/kwa_home/wp-content/uploads/2018/02/Ronin_Motor_Current-1.jpg

 

SWITCH LIFE EXTENDER (SLE)

THE NEW GENERATION: AEG 2.5

Get more pew pew out of your new KWA AEG 2.5 with the new Switch Life Extender, included on all new gen AEGs. The SLE will extend the life of your trigger contacts by almost 500% by absorbing 99.9% of the back current/power surge that cause their shuttle contacts to burn out.

Unlike other electrical aftermarket add-ons, the SLE doesn’t rely on complicated circuit boards or cause erratic trigger behavior. Combined with numerous internal upgrades like the adjustable fps, the new gen of KWA AEGs is the new standard

 

 

Yeah - I think it is a basic flyback diode or RC snubber circuit

(Resistor & Capacitor - hence RC snubber, nowt to do with RC toy cars)

 

Bit like ICS was banging on about yonks ago to reduce arcing at trigger

a 20p diode but call it KWA's new SLE system - still at least it works

 

minor trade off: diodes nick a bit of juice - forward voltage drop to turn on

so they tend to nick 0.5v~0.7v to turn on

 

BUT with all the circuitry in them fancy mosfets with bells & whistles

they too are nicking a bit of juice too...

 

yup some diode or RC snubber bollox...

 

good ol' Pheas, though snubber/flyback not anti shorting system

 

 

 

FFS chaps it is a flyback diode most likely - not some fancy rocket science engineering

(could be RC but I'd say a straight up diode)

 

 

 

Adjustable fps -  JG was using some crude but similar in their G36's & SIG's

 

 

basically it is a metal spring guide - with a fine grub screw that pushed the outer sleeve of spring guide up

probably about 5mm travel, almost 2 extra teeth compression, meaning about 30fps tweak-able

wasn't a spring guide, though it did rotate slightly between two halves so allowed for "some" slight spring twist

very crude but effective option to slightly tweak final spring power/fps

If the JG box had a hole in the rear of it, at the two halves, then chances are it had a tweak-able spring guide in there

 

On the G36 - good idea as box is enclosed at back when folding stock

On the SIG - not bad, but as box is more exposed - wtf didn't you fit a QC box in there JG ???

(it is crying out all ready for it on the SIG - jeez)

 

There was other companies that brought out tweak-able spring guides

but probably didn't catch on due to a bit of fiddling/modding to get easy access to tweak the spring guide

and like the SIG if you got really easy access then QC box would be better maybe

(and I guess with a little mod the G36 could be opened slightly to allow a QC v3 box perhaps)

 

Some clever stuff out there, some very fancy stuff & clever engineering driving things forward

[Skara]

So, etu went in, but the safety isn't working anymore and the screw that holds it down stripped the fucking shell.

Maybe I'm just retarded, but every time I try to fit one, some weird shit happens.

I'm not willing to drop another €150 on a Titan, so I'll just wait for a Perun V2 to come back in stock on some cunt website and install it.

I just need binary and precocking, nothing more.

Plus a Lonex A1+ if my team's tech lets me have it for not much (otherwise it's gonna be the usual SHS HT or similar)

[Lollingsgrad]

50 minutes ago, Skara said:

I'll just wait for a Perun V2 to come back in stock on some cunt website and install it.

 

TaiwanGun's got it but delivery fees are killers and they're not as cheap as, say, Bullseye Country Sport who stock it but are out.

 

https://www.taiwangun.com/mosfet-wires/mosfet-perun-v2-optical-back-wired-perun?q=Perun+op&campaign-id=14

 

You could also give contacting Perun directly a punt, they responded in a day last time I emailed them.

[Sitting Duck]

7 hours ago, Skara said:

So, etu went in, but the safety isn't working anymore and the screw that holds it down stripped the fucking shell.

Maybe I'm just retarded, but every time I try to fit one, some weird shit happens.

I'm not willing to drop another €150 on a Titan, so I'll just wait for a Perun V2 to come back in stock on some cunt website and install it.

I just need binary and precocking, nothing more.

Plus a Lonex A1+ if my team's tech lets me have it for not much (otherwise it's gonna be the usual SHS HT or similar)

 

Did you use the G&G "DMR" type selector plate

or mod the KWA selector plate for semi only ???

 

If you used the G&G selector plate, the "arch" might be in a very very slightly different position

hence in rare occasions a new/different selector plate can throw out the semi/auto setting

& even the safety too...

 

I had that once, think it was a Cyma selector I broke on my first CM.515

the replacement was lovely - except for safety not quite working

what it was the slide by switch was a little different and it was only raising the safety arm halfway

& not lining up with trigger safety lug, slipping just under it & allowing trigger pull

So the new plate was cut different to Cyma, but they have copper clip on selector...

 

So I added a small strip of solder to the copper plate by safety arm

enough to fully raise safety arm & stop trigger being pulled

 

Comparing the 2 selector plates on top of each other - the "arch" is basically cut about 1.5mm different place

so the "tab" was never going to raise the safety properly

miracle the fire semi/auto worked OK - guess the arch & COL area was within tolerance

but it was safety that was real problem for compatibility

 

So if you used the pre-modded semi only G&G ETU selector plate, the safety tab end might be different

thus not raising the safety arm 101%

use the KWA plate & mod the COL area like DMR

 

stripped screw, larger screw or thread lock/spec of glue/epoxy to re-thread/bind it

 

I ALWAYS or nearly always place the small threads - even the M3 gearbox bolts

place them in, then turn COUNTER CLOCKWISE until you feel the screw rise up & "bump"

THEN tighten up screw, as the screw has located & aligned itself 101% with thread

 

Been modding consoles & other shit for ages and found if you just slap screws in you tend to

re-cut the threads of the plastic cases if take them apart more than a couple of times

so much so they weaken and soon strip

 

The unscrew to locate, "bump" & tighten method really reduces the risk of cheap shitty threads stripping

when I see people just chucking in gearbox screws & tightening straight away - with electric driver too

I think rather you than me type of thing, coz I found the back & bump method to locate the thread

really works to ensure the tiny screw/bolt properly finds the fine thread, than risk trying recut/widen it

 

in my defence I took an OCD online test & scored 101%, I got 100% of course

but I noticed the result page was off-centre - autistic screeching goes into overdrive 

(pretty sure there was a typo too but was yonks ago - it was page not aligned that really freaked me out)

 

 

joking aside, we all have a bit of OCD & though we mock it at times...

Michael J Fox in Scrubs played an amazing brief role as top doctor/surgeon Kevin Casey with OCD

who was so good at everything he starts pissing everybody off

I can relate to that - not being amazingly good, fuck no

but pissing everybody off bit - yup that's my speciality (ask Mrs Duck)

 

 

I'M NOT THAT BAD, only coz now I don't look quite so closely at things

[Skara]

I'm not that retarded Duck

i know how to properly tighten a screw lol.

 

Regarding the safety, I used a G&G plate (DMR type), didn't touch the mechanical safety at all.

I say there's an incompatibility between the KA safety lever and the G&G etu trigger board, because with the regular KA switch the safety works properly, with the ETU it becomes super stiff to operate, and once the G&G selector plate pushes to the front to engage the safety latch, this one is so stiff that when switching to semi does fuck all and the safety bar jams in position.

 

But no biggie, I found a Perun V2 at a reasonable price, gonna order another MAXX trigger as well (maybe gold this time?) and go from there.

 

The only decision left to make is about gear ratio and motor.

[Sitting Duck]

Gear ratio might depend if box is reinforced

requiring mod for 13:1's like some King Arms, Cyma's even M904G

(not all cyma v2's, the new QC Cyma v2's, the 7mm mp5's not reinforced)

 

Not a biggy mod if required for 13:1's

But something to consider when planning

If box is strong enough - just drop DSG in

& run a torque 28tpa with 150/160 spring option ???

 

Guess it depends what motor you end up getting

Lonex A1 then maybe keep stock gears

SHS or 25k or 22 TPA maybe 13:1's

Old crappy 27 tpa motor, strip & chuck in neodym can & DSG ???

 

But like everything, where do ya start & where do ya stop I guess

[Skara]

Perun installed, something must have gone terribly wrong though, as after the calibration process now whenever I plug the battery in the gun fires on its own.

 

EDIT:

What went wrong was me messing up the calibration.

Took it apart, tricked the unit into calibration mode and made the trigger pull a bit more substantial than the touch screen I had set

seems to be working fine now, although it's rather late now and can't test properly.

 

also reshimmed the box, it runs somewhat smooth now (spur gear was too tight from factory, while the sector and bevel were really loose) with only just a tiny bit of play on the sector, so tiny that if I put a 0.1mm spacer it becomes too tight.

 

Now we (I) wait for a zci 22tpa and 13:1s so that I can meme around with binary spam

 

EDIT 2:

Out of curiosity I installed one of my SHS high torque motors and ho-lee shit it's fast!

Double taps like a motherfucker without AB.

 

So yeah, I'll keep the stock gears and order yet another SHS HT.

[Skara]

Forgot to update this thread.

 

In the end I went for a ZCI 22tpa motor, quite slow but the semi cycle time on a 11.1 is good.

 

The gearbox shell, though is utter shit, or the motor is, or the grip, I can't figure it out -.-

I can't properly shim it, I did the good ol' spur first but the bevel wants to sit really high.

Tried bevel to pinion, the bevel now has zero shims on top yet it appears to be too tight, moreover the ZCI motor is really pushing against the bevel even with the grip adjustment screw completely removed.

 

I thought it was the gearbox shell being a bit shit, so I bought an 8mm one but the bearings I got (SHS) must've been a friday night job and they don't spin -.- stayed up until 2 AM last night to try and figure out what was going on and I'm really pissed.

 

I'll see if I can pick up a set of decent bushings later today and try again -.-

[DerDer]

A few companies seems to advertise low profile bushings. Might be worth a go?

It's very frustrating to repeatedly take apart and assemble a gearbox, if the screeching is caused by wonky bearings

rather than one's own shimming.  

[Skara]

On 24/02/2021 at 11:28, DerDer said:

A few companies seems to advertise low profile bushings. Might be worth a go?

It's very frustrating to repeatedly take apart and assemble a gearbox, if the screeching is caused by wonky bearings

rather than one's own shimming.  

Bushings profile isn't the issue.

It's how they went in and the fact that they don't spin (well one does but still, 1/6 is not good enough lol).

I'll pick up some decent ones this Saturday.

In the meantime I started dicking around with various parts and decided to try a different pistol grip.

Swapped the stock one for an old ICS grip I had and it made a world of difference!

The stock grip, as mentioned above, makes the motor sit way too high despite having removed the adjustment screw.

The "new" grip, on the contrary, almost completely removed the pinion to bevel scratching, although now it doesn't sit flush but is slightly canted to the side and the motor gets warm quickly.

There is still some gear scratching noise but that will eventually go away as soon as I replace the bearings.