Ak12 Low Joules

[george1976]

Hey guys

I recently  purchased an Arcturus AK12 in good used state and I was a bit disappointed when I had it chronoed before a game and was doing 0.7Joules. I didn’t asked for FPS at the time, my bad.

Gun is shooting like a laser and has no issues with feeding but I feel like it is underpowered somehow.

I took the gun apart and compression is excellent without the air nozzle , and just decent with the stock air nozzle which has an oring.

There is a 450mm barell and looks like a 4/5 cylinder, not fully closed.

I am trying to up the power and I have in my shopping basket a high torque motor and a new nozzle together with a Maple Leaf macaron and nub.

Should I upgrade to a full cylinder also?

What do you think it will help me get to some 1.1 Joules. Maybe a spring?

Running on a 7.4 Li po at the moment, thinking about a mosfet and 11.1 maybe.

If I fix this issue I can declare myself extremely happy with the gun in the end ?

Thank you and sorry for the text wall ?

 

[EDcase]

A full cylinder will help up the power.  New motor and Maple Leaf will not do much in that regard.

A stronger spring is the main component affecting power once you've checked the air seal is good.

Someone will help with the best spring...   (My guess is M110 or M120)

Going from 7.4v to 11.1v will cycle faster but put much more strain on components.

 

[Rogerborg]

Hmm, Luke at Negative got pretty much 0.7J out of an Arcturus after a rebuild with a new barrel and hop rubber, and I'd assume he took care over the air seal. But the stock spring looked awful, and woefully under-sprung.

Depends how much time or money you want to put into it, I guess. Either start with an M100 then buy higher if you need it, or get an M110 or similar, and trim it down if necessary - the spring change doesn't seem too onerous.

 

[BigStew]

What weight of BBs did you chrono it on?

 

[george1976]

I had it on .28 chronoed, I have seen Luke’s video and it’s not clear what he did, someone joking he just swears at it ?

I believe it was the air seal also. Now I have it open and have very good compression with the barrel and hop unit on and stock bucking.

Inner barrel is mirror like also.

 I am now looking to see if the nozzle does a french kiss with the bucking as it should ?

Should I even think about changing the stock motor?

Thanks for the replies gents.

3 hours ago, Rogerborg said:

Hmm, Luke at Negative got pretty much 0.7J out of an Arcturus after a rebuild with a new barrel and hop rubber, and I'd assume he took care over the air seal. But the stock spring looked awful, and woefully under-sprung.

I have some things in basket from ak2m4 and I will get a new spring also.

Already have a 130 from when I tried it on my sons CXP HOG 275, but I am thinking it’s too strong maybe. Thanks 

 

[george1976]

Hmm, I do not like how long the nozzle goes into the hop unit, had the impression that the tappet plate was keeping the nozzle a bit retracted but I though was just me, have to dig a bit deeper 

 

[Rogerborg]

Looks like he changed the spring, that stock spring is weaker than a politician's promise.

If the air seal is half decent, an M100 should get it up to at least a Joule.  And barrel length just isn't that important.  I accidentally got a surprising 1.3J out of an M100 with a stock budget CYMA gearbox, ZCI rotary hop and a ZCI 6.02mm 229mm barrel, just by nailing the air seal, and had to drop to an M90 to get down to 1.1J.

On that, I'd check that the barrel is fully seated in the hop, shove it in like... a politician with a drunken intern.

I really don't like politicians, I'm not sure if that's coming across.

 

[Shamal]

Looks like he changed the spring, that stock spring is weaker than a politician's promise.

If the air seal is half decent, an M100 should get it up to at least a Joule.  And barrel length just isn't that important.  I accidentally got a surprising 1.3J out of an M100 with a stock budget CYMA gearbox, ZCI rotary hop and a ZCI 6.02mm 229mm barrel, just by nailing the air seal, and had to drop to an M90 to get down to 1.1J.

On that, I'd check that the barrel is fully seated in the hop, shove it in like... a politician with a drunken intern.

I really don't like politicians, I'm not sure if that's coming across.

Just a wee bit......?

 

[george1976]

Looks like he changed the spring, that stock spring is weaker than a politician's promise.

If the air seal is half decent, an M100 should get it up to at least a Joule.  And barrel length just isn't that important.  I accidentally got a surprising 1.3J out of an M100 with a stock budget CYMA gearbox, ZCI rotary hop and a ZCI 6.02mm 229mm barrel, just by nailing the air seal, and had to drop to an M90 to get down to 1.1J.

On that, I'd check that the barrel is fully seated in the hop, shove it in like... a politician with a drunken intern.

I really don't like politicians, I'm not sure if that's coming across.

It's coming across just fine, had some strong words towards them when TaiwanGun replied to my email saying that I cannot order from them at the moment, and to order from their distributor Patrolbase............. For some stupid reason no tariffs deal with EU translates into a lot of hassle with customs and out of stocks in airsoft related shops.

 

[Druid799]

The missing question is what kind of range you got with it ?

 

[Rogerborg]

The missing question is what kind of range you got with it ?

Less than he'd get with a consistent 1.1J and the same hop and barrel, I'd hazard.

 

[george1976]

The missing question is what kind of range you got with it ?

When they told me the Joules I deflated and did not care about that ?, but yeah, like Rogeborg said: less than I expected but not a lot less so to make me stop playing.

I have ordered a full cylinder, with the M100 springs I was unlucky with the stock where I did my shopping late yesterday, I have a new shs nozzle also, will start working on it and will definitely update this once I’m done.

 

[Druid799]

Less than he'd get with a consistent 1.1J and the same hop and barrel, I'd hazard.

You never know ? ?

 

[Rogerborg]

You never know ? ?

Only if physics starts working with all the consistency and rationality of a Parliamentary select committee.

 

[Druid799]

Only if physics starts working with all the consistency and rationality of a Parliamentary select committee.

No simply commenting on what we’ve all seen occur at some time or another , low FPS but range and accuracy fair to ok , change to a stronger spring but everything else remains the same and suddenly range and accuracy goes to rat shit . It happens . 

 

[george1976]

Having problems with the new SHS nozzle and the old cylinder head....... No seal. I wonder if ordering a new shs cylinder head would make a difference, or a new aols nozzle, I hear they have thicker orings.

The fun...... ?

 

[Adolf Hamster]

No simply commenting on what we’ve all seen occur at some time or another , low FPS but range and accuracy fair to ok , change to a stronger spring but everything else remains the same and suddenly range and accuracy goes to rat shit . It happens . 

that it does, although almost exclusively linked to issues in re-assembly rather than the power change in and of itself.

being horrifically underpowered is unfortunately rather common, if it's a bit spicy and needs a downgrade retailers have a nasty habit of just whacking in the flimsiest spring they can find and calling it a day. needless to say this can cause problems (especially pme related problems) on some guns.

the only shop i've seen do it properly is gunfire- they actually cut the spring and do a pretty damn good job of getting within, but not stupidly under, the limit.

 

[Rogerborg]

the only shop i've seen do it properly is gunfire- they actually cut the spring and do a pretty damn good job of getting within, but not stupidly under, the limit

I'd suggest that TaiwanGun do it as well.  Or at least I bought a CYMA M4 from PatrolBase which was likely wholesold from TaiwanGun with a cut spring that was bang on 1.1J.  There was almost no pre-tension on it, but it worked just fine.

And, sure, you can have a gun that shoots beautifully out to the maximum range for its energy, then make it less accurate with a hotter spring.

But you can also add a hotter spring and retain or improve the consistency.  Why settle for one?  Airsoft guns do not run on magic: if you want the maximum possible range, you need to be shooting your chosen BB weight fully hopped at the site limit.  It's not sufficient, but it is necessary.

 

[Adolf Hamster]

I'd suggest that TaiwanGun do it as well.  Or at least I bought a CYMA M4 from PatrolBase which was likely wholesold from TaiwanGun with a cut spring that was bang on 1.1J.  There was almost no pre-tension on it, but it worked just fine.

quite possibly, never bought a gat from tg but i wouldn't be surprised if they did the same.

 

[george1976]

Hello again.

I have installed a XT anti heat full cylinder together with an M100 Rocket spring but I was forced to leave aside the SHS AK cylinder head and SHS AK nozzle because they wouldn't match  

Almost 0 air seal between the shs parts, one would expect products from the same company designed for the same replica to be a good fit ?

So I left the old cylinder head and nozzle in place, greased them well and I get 1.03J and 338FPS with 0.25BB now.

The brand new xcortech that measured this unfortunately doesn't count the rps, I think Amazon sent me a returned one, not sealed, batteries missing.

I also installed a macaron rubber, will see how it works.

I must have done a very good (or bad) job at shimming because it now sounds like a pneumatic weapon, no gear sound. ?

On another front I did the compression on my son's Valken mk3 and messed up the plastic motor plate right at the end...........

Needles to say the brand new Element M4/M16 grip doesn't match the brand new Element M4 motor plate  :huh:  and the way I forced the screws in I messed up something, smell gives it away

Now I have to sort that out, was thinking at the only grip ak2m has in stock right now, but I am a bit worried about how that "door" closes on the end of the motor, will see.

Thanks for the advice.

Later edit: correction on the Xcortech. With stock gears and 7.4 it registers the lame 11rps a bit slow..... I get 16rps on the 11.1.