Double Eagle M906C - Internal upgrades / tinkering

[Adolf Hamster]

Yeah, that second bunch of chrono results are the Specna 0.28's, so around a 3fps variance!

ahh, sneaky editing

still some room for improvement with the air seal then, but as with all these things it depends on where your personal standard of "good enough" lies.

shame about the wind, as curious to see what the spread is as-is with what i'm guessing is still the stock barrel?

 

[RostokMcSpoons]

Yeah, still the stock barrel.  Perhaps some day I'll get a longer, maybe tighter-bore one, running it through the suppressor

Is +-1.5fps (3fps in total) not pretty damned good?

 

[Adolf Hamster]

Yeah, still the stock barrel.  Perhaps some day I'll get a longer, maybe tighter-bore one, running it through the suppressor

no need to make it any longer/shorter, better to stick to the original length. i'm curious to see what a ZCI 6.02 will do to the grouping as they're damn good barrels (especially given the price)

Is +-1.5fps (3fps in total) not pretty damned good?

ahh, see i'm including the full range (the 280.8 and 276.8) and i have unrealistic standards

 

[RostokMcSpoons]

I see what you mean about the ZCI barrels... I could replace the existing 240(?)mm one, or jump up to 340mm for ~£21

That's not bad, not bad at all!

But I see what you're up to now, you sneaky man!   You're spending my money and upgrading by proxy, call it "Shithausen's Syndrome" 

Edit: I'll run a few more BB's down the range if it's less windy tomorrow, to get a better take on the current accuracy.

 

[Adolf Hamster]

I see what you mean about the ZCI barrels... I could replace the existing 240(?)mm one, or jump up to 340mm for ~£21

That's not bad, not bad at all!

aye, bang for buck i'd say they're one of, if not the best options out there atm.

But I see what you're up to now, you sneaky man!   You're spending my money and upgrading by proxy, call it "Shithausen's Syndrome" 

in fairness, i am starting to wonder if you're getting near to that being the limiting factor. as with all things it depends on how far you want to go in terms of when you think good enough is good enough.

Edit: I'll run a few more BB's down the range if it's less windy tomorrow, to get a better take on the current accuracy.

yeah, particularly see if that's the main cause of the horizontal spread.

 

[RostokMcSpoons]

in fairness, i am starting to wonder if you're getting near to that being the limiting factor. as with all things it depends on how far you want to go in terms of when you think good enough is good enough.

I think now I've got a consistent muzzle velocity that's holding the same day-to-day, it has now reached "good enough".  But I was a bit taken aback when someone else mentioned getting 65m hits with their DE.  To be fair I've got no idea what my gun will shoot to now, I'm limited to 18-20m max at home, so I'll not fret too much until I've got out to the site again. but that seems unlikely for mine if I'm already grouping at 3-4" at only 15m.

Most of my focus is back on the F2000...

I've also got my AK47 which is currently dead due to a blown fuse, and needing the nozzle replaced - so another v3 gearbox opening.  Ho hum.
And my CA M15 is still shooting off to the right again, and also down at 270fps so that needs a spring change.  And I might change the front end for a VN M16 handguard... cos they're cool.  

So plenty to muck about with still!

 

[Adolf Hamster]

But I was a bit taken aback when someone else mentioned getting 65m hits with their DE.

always take claims of airsoft range with a big heap of salt, for starters airsoft meters are well known to be a different length to metric meters, and many folks will have different versions of what they mean by getting hits, dumping half a magazine into space for one round to barely be noticed, or firing one shot straight and level and hitting every time, wether it's a full target or someone hiding in cover etc.

but that seems unlikely for mine if I'm already grouping at 3-4" at only 15m.

eh, can be tricky to tell. i've never done any proper range testing always went with just how it felt in the field.

 

[RostokMcSpoons]

Well... damn it.

The gun I never wanted to crack open and meddle with, needs cracking open and meddling with.

I tried to do the quick change spring thing, to see if a new M105 would lift my fps back to the 345 fps I chrono'd at recently, and that simple job went a bit awry.  As I pushed the spring guide in, it felt like the spring popped downwards and the spring guide went deeper into the gun than I expected.  I took it back out and cycled the gun without a spring, and it works... but it's now got the piston all the way to the back.   I think I've managed to get things out-of-sync (but I'll take advice on that).  With the piston backwards it's going to be hellish to force the spring in, but it feels like a bad idea anyway...?

(Edit: I realised I could manipulate the bevel gear, and that got the piston forward.  I re-installed the spring, but the gearbox clicked and the fire control unit beeped back at me when I tried to fire.  So yeah, something is officially askew on treddle.   The motor still runs when out of the pistol grip, so I've not killed that or the mosfet)

So I'm now at the point where I'm taking my beloved rifle apart, not really being able to remember how M4 / V2 gearboxes are disassembled.  I can't get the gearbox out of the lower receiver, though I've taken off the pistol grip, the selector switches, popped out both big body pins, and also the thin pin above the trigger.

The remaining thing retaining it in place now seems to be magazine catch bar that runs across the body, and through a hole in the gearbox.   I'm not entirely sure how to remove it.  Any hints?  I can only find YT videos of the 904 and that seems to be built a little differently - there's a removable screw in the mag catch on the right side of the receiver that doesn't seem to exist on mine.
 

View attachment 102838

Any thoughts, as always, hugely appreciated

 

[Adolf Hamster]

that type of mag catch looks to be the type that the bar is threaded into the button, so you gotta push the button all the way in then unscrew the other side.

they're a bit of a pain as often the bolt catch paddle needs to be removed to give clearance.

as for the spring, sounds like initially it got kinked and dropped downwards, not really a big deal unless it gets stuck or bent permanently, just pull it out and reinstall.

for the piston in the rear position, the lazy way to solve that without cracking the gearbox is to use a flat ended tool (a punch or a flat ground hex driver, basically anything that won't scratch the piston head more than you're happy with) up through the nozzle to push the piston all the way back then it'll usually be able slide forward again. you don't have to pull the motor, but doing so will reduce the force required to push the piston back.

at the risk of creating a "do'h" moment the clicking after reinstalling the motor, sounds very much like the polarity of the motor is reversed, so it's running backwards into the arl before the mosfet kicks in and starts complaining.

 

[RostokMcSpoons]

Thanks!   The mag catch was just as described.  I was trying to take the bolt catch paddle off, but still can't figure that out.  Anyway, with a bit of persuasion the mag catch bar did let me unscrew it over the top of the paddle.
So now the gearbox is retained just by the bolt catch ambi connection.   :Sigh: 

I did take care about ensuring the motor was the right way around and attached to the leads correctly... but hell, I could still have done it wrongly.

What worries me now is that the piston is able to move backwards and forwards freely inside the cylinder... there's nothing engaging with the gear   Has the rack perhaps stripped out from the piston?   I can't hear anything rattling around, nothing seems broken as such

 

[Adolf Hamster]

Thanks!   The mag catch was just as described.  I was trying to take the bolt catch paddle off, but still can't figure that out.  Anyway, with a bit of persuasion the mag catch bar did let me unscrew it over the top of the paddle.
So now the gearbox is retained just by the bolt catch ambi connection.   :Sigh: 

that's the joys of the m4 platform for you......

I did take care about ensuring the motor was the right way around and attached to the leads correctly... but hell, I could still have done it wrongly.

honestly motor wires are like usb sticks or unlabelled push/pull doors, despite there being only 2 ways to do it they unfailingly require 3 attempts to get right

What worries me now is that the piston is able to move backwards and forwards freely inside the cylinder... there's nothing engaging with the gear   Has the rack perhaps stripped out from the piston?   I can't hear anything rattling around, nothing seems broken as such

is it not just the sector still sitting in the "firing" point of it's cycle? or are you turning the gears over and it's not moving the piston?

 

[RostokMcSpoons]

I'm trying to turn the gears, but now I've looked again, it seems it's springing back and I've not really been turning anything.  So yeah, quite possibly still in firing position.  I presume it's either the ARL or tappet plate spring providing the resistance? 

Worth just putting it back together and trying again?

Awww damnit, I'll give it a go


View attachment 84996

... bet ya I had the motor in back to front ;]

 

[Adolf Hamster]

I'm trying to turn the gears, but now I've looked again, it seems it's springing back and I've not really been turning anything.  So yeah, quite possibly still in firing position.  I presume it's either the ARL or tappet plate spring providing the resistance? 

depending on where it is tappet plate would be the most likely culprit

... bet ya I had the motor in back to front ;]

just act casual and hope nobody noticed, that's what i always do

 

[RostokMcSpoons]

It's alive, but I have buggered it a bit. 
I lost the tiny spring from the selector lever.   I've still got the tiny ball bearing, but the spring (which was along side) must have got attracted to something magnetised (like one of my allen keys), or caught a gust of air and gone walkies.  It's too small to find, I just hope it's not inside the gun ;/

Maybe as a result of the lever being able to move too easily, or because I didn't align the selector somehow, it's now sometimes beeping rather than shooting.  

To add insult to injury, it's chrono-ing at much the same velocity as it was before I started all this palaver - there was nothing wrong with the spring.

@ak2m4  do you have the detente springs in stock - or know what size I need to get off eBay / Amazon?

 

[Adolf Hamster]

I lost the tiny spring from the selector lever.   I've still got the tiny ball bearing, but the spring (which was along side) must have got attracted to something magnetised (like one of my allen keys), or caught a gust of air and gone walkies.  It's too small to find, I just hope it's not inside the gun ;/

oh dear, it's definately migrated it's way to outer mongolia by now.......

 

[RostokMcSpoons]

Hahaha the problem with it not shooting... I have a Deans extension cable on the gun, to make connecting the battery easier.  To 'make sure' it doesn't get disconnected, the connectors are wrapped in electrical tape... which had hidden the fact it was very nearly disconnected!

Without the stock, the battery was occasionally dangling from the gun... it had pulled apart to the point there was just a tenuous connection - when I moved it, it would either make or break, setting off the (connection) beeps.

I am SO relieved I haven't broken my lovely gun.   Now I just need to get a decent fix for the selector lever.... 

 

[ak2m4]

@RostokMcSpoons I don't really,  I have some longer ones which seem the right OD but from experience I've noticed brands use all sorts of different sizes.  Maybe someone can measure one?

 

[RostokMcSpoons]

@RostokMcSpoons I don't really,  I have some longer ones which seem the right OD but from experience I've noticed brands use all sorts of different sizes.  Maybe someone can measure one?

The ball bearing is 2.4mm diameter, so, bearing* that in mind and from my (goldfish) memory, I'm going to say ~2mm diameter, 3-4mm long would seem right, it was a tiny spring.

Edit: Pics on my new Fire selector thread
I could buy the mixed pack from this eBay page and cut one down to size...?

* Pun not intended, I wish it had been 

 

[ak2m4]

The ball bearing is 2.4mm diameter, so, bearing* that in mind and from my (goldfish) memory, I'm going to say ~2mm diameter, 3-4mm long would seem right, it was a tiny spring.

Edit: Pics on my new Fire selector thread
I could buy the mixed pack from this eBay page and cut one down to size...?

* Pun not intended, I wish it had been 

 
let me have a quick look this afternoon and I'll send you some over, I'm sure I'm got loads which will fit ?

 

[RostokMcSpoons]

I watched a short video about fitting replacement selecter levers, where the guy complained about the fact the spring and ball are often not supplied.  He suggested using a Cutoff Lever spring, cut down to the right length.  So that might be a better guide than my bad memory for what the original looked like