A little while ago, I picked up a second hand Specna Arms M16/M203. It was advertised as having a Madbull Barrel and Hop unit and High Speed motor.
Got it in and it was firing roughly 365 fps and really struggled to pull anything on a 7.4v lipo.
I removed the knackered Lonex High speed motor and installed a new GP 22TPA Neo. Much better trigger response and 7.4v lipo works fine with it.
I forgot about until recently, working from home means I tough i would use the E&C system and install a new spring. Having never taken apart any part of a standard M16/M4 I knew it would be interesting. Also had a Mosfet to go into it.
Well, I couldn't FIND the E&C system... this is what greeted me.
Yup, that's right folks. Whoever teched this replaced the Specna internals with all G&G ones. So no easy spring change, the Hop unit and barrel was G&G stock, chewed up air nozzle and a janky ass flat hop with a guarder clear.
Pretty annoyed as I have never worked on a V2 gearbox before. Now going to put together a parts list to replace most of it. Far too late to get any money back from this. Luckily the G&G gearbox shell itself is pretty good.
So what shall I do?
Get a new Specna or improved GB shell?
New airseal components? Gears etc?
I am definitely getting a new ZCI barrel and maybe a rotary hop unit.
Looks like @ak2m4 will be getting more of my custom...
Yup, that's right folks. Whoever teched this replaced the Specna internals with all G&G ones. So no easy spring change, the Hop unit and barrel was G&G stock, chewed up air nozzle and a janky ass flat hop with a guarder clear.
Pretty annoyed as I have never worked on a V2 gearbox before. Now going to put together a parts list to replace most of it. Far too late to get any money back from this. Luckily the G&G gearbox shell itself is pretty good.
So what shall I do?
Get a new Specna or improved GB shell?
New airseal components? Gears etc?
I am definitely getting a new ZCI barrel and maybe a rotary hop unit.
Looks like @ak2m4 will be getting more of my custom...
So with the gearbox shell; unless it's cracked, it will probably be fine for your purposes. M16 is a metre long rifle so I imagine you wont be taking this to CQB, i.e get it dialed in for 350 and leave it - no QD spring really needed. G&G shells are pretty good - they are not your cheap ACM pot metal.
Once you get inside the V2 you will want to check out the condition of the piston teeth. But unless there are serious air seal issues it may be good to go regarding piston and cylinder heads - sounds like you need a new nozzle so maybe a nice metal one with an oring seal.
Make sure semi is functioning perfectly and inspect the cut off lever while you are in there.
Check the shimming.
clean and then lube it up.
One thought; you have it setup as an M16A3 - Semi/Auto. If you wanted to you could treat it as an A4 and put a burst switch/mosfet/chip inside... plenty of room in the stock of an M16, maybe a Warfet?
Obviously that's down to your own preference. I've had a lot of fun when my burst A2 has been working!
Obviously good shout with a new barrel/rotary hop/rubber. As always I would go maple leaf for the rubber and nub.
Either way, enjoy mate... full length M16s are awesome and manly! ?
by the sounds it looks like at least the nozzle is going to need changed. personally i like the brass type with a sealing o-ring rather than plastic/aluminium.
you can do a few tweaks to improve the air seal, of course if you want to spend then certainly replacing the cylinder head/cylinder/piston head won't be too bad.
if the gears are in good nick and you don't want to do any stupid rof shenanigans then probably just leave them as-is, piston as well if it's in good condition.
quick change springs do make working on the box an awful lot easier, and as a quality of life thing i would say it's worth it, although there's nothing fundamentally wrong with just running the g&g shell as is, it's not like getting the box out enough to swap the spring isn't already a pain in the ass.
hop wise i've been really impressed with the MAXX units, dunno how well they fit specna's (i'm running an e&c reciever with a fusion engine) but the performance is amazing, a maple leaf macaron with the included R-nub and on a zci she's doing sterling work (although granted i do plan on swapping the barrel before long because muh pdi)
So with the gearbox shell; unless it's cracked, it will probably be fine for your purposes. M16 is a metre long rifle so I imagine you wont be taking this to CQB, i.e get it dialed in for 350 and leave it - no QD spring really needed. G&G shells are pretty good - they are not your cheap ACM pot metal.
Once you get inside the V2 you will want to check out the condition of the piston teeth. But unless there are serious air seal issues it may be good to go regarding piston and cylinder heads - sounds like you need a new nozzle so maybe a nice metal one with an oring seal.
Make sure semi is functioning perfectly and inspect the cut off lever while you are in there.
Check the shimming.
clean and then lube it up.
One thought; you have it setup as an M16A3 - Semi/Auto. If you wanted to you could treat it as an A4 and put a burst switch/mosfet/chip inside... plenty of room in the stock of an M16, maybe a Warfet?
Obviously that's down to your own preference. I've had a lot of fun when my burst A2 has been working!
Obviously good shout with a new barrel/rotary hop/rubber. As always I would go maple leaf for the rubber and nub.
Either way, enjoy mate... full length M16s are awesome and manly! ?
by the sounds it looks like at least the nozzle is going to need changed. personally i like the brass type with a sealing o-ring rather than plastic/aluminium.
you can do a few tweaks to improve the air seal, of course if you want to spend then certainly replacing the cylinder head/cylinder/piston head won't be too bad.
if the gears are in good nick and you don't want to do any stupid rof shenanigans then probably just leave them as-is, piston as well if it's in good condition.
quick change springs do make working on the box an awful lot easier, and as a quality of life thing i would say it's worth it, although there's nothing fundamentally wrong with just running the g&g shell as is, it's not like getting the box out enough to swap the spring isn't already a pain in the ass.
hop wise i've been really impressed with the MAXX units, dunno how well they fit specna's (i'm running an e&c reciever with a fusion engine) but the performance is amazing, a maple leaf macaron with the included R-nub and on a zci she's doing sterling work (although granted i do plan on swapping the barrel before long because muh pdi)
Not looking to spend that much, so probably wont be going for super fancy hop units like the Maxx, I am sure something like a metal SHS or ZCI will be fine, though I am not sure exactly which one I should go for.
I will likely go for a Brass or Aluminium type nozzle. Something like an SHS.
I was thinking of a QD gearbox mostly because I really think they make things so much easier testing after a new build, adjusting springs etc to compensate for too much FPS or overspin etc. But I can probably stick with the G&G box as I hear they are pretty good. AK2M4 have Specna QD Gearbox shells with bushings and Spring guide for quite cheap though if I wanted. Semi and shimming seem absolutely fine and RPS is perfectly fine with the High torque neo motor I have in their now.
I can probably get away with the current Air Seal components as is, but I might as well replace while the box is open.
Just a basic mosfet, I have a PERUN one ready to go in. Maple Leaf Macaron is already in their with a 0hm nub.
I reckon it will be firing hot with my usual M95 spring, good air seal and a ZCI 509mm inner barrel. Will there be any stability problems if I go for a shorter barrel, say around 400mm?
My gearbox parts have come in so decided to give it a go!
Opened up the gearbox and this is what awaited me. Again, the internals being a surprise.
The gearbox has clearly been worked on. The Gears are 13:1 SHS, Aftermarket piston with 13 1/2 teeth, stock brass cylinder, Lonex POM piston head and Lonex Aluminium Cylinder head. Basic metal spring guide. Slightly worn anti reversal latch but good otherwise. Standard wiring. So the original build had a High Speed G&P Ferrite motor, paired with a 13:1 gearset, no wonder it only turned on a 11.1v lipo. But had no mosfet installed! AOE is correct.
The Spring is quite a strong one.
The air seal components are really good so will be keeping them, very good seal.
Slightly worn piston.
The original black POM nozzle looks like it had been shaved down slightly as it's shorter then my replacement. Air seal is good with the Cylinder head so I am unsure whether to replace with the new one or not.
It could have been shortened because of a feeding problem. What do you guys thing I should do?
Shaved down the 13th Tooth on the new piston as the Sector was hitting it.
Project has stopped here, having never broken into a V2 box I was surprised how little space I had for wiring. Pictured is the thinnest wire I had which is too thick to add an additional wire for the mosfet. So have had to order some 22AWG. Until that comes through I'll have to sit tight!
looks like there's a bit too much sorbo been used for the AOE there, would explain why the sector was hitting it.
is there a thrust bearing inside the piston? personally i'd rather have a bearing on the spring guide and keep the piston as light as possible, especially to try and avoid PME issues for zippier builds.
you could give the nozzle a go, if it still feeds then the extra length is going to help it seal against the feed lips a bit better.
is there a tappet delay chip on the sector? might be worth investing if there isn't as that can help clear up feeding issues.
looks like there's a bit too much sorbo been used for the AOE there, would explain why the sector was hitting it.
is there a thrust bearing inside the piston? personally i'd rather have a bearing on the spring guide and keep the piston as light as possible, especially to try and avoid PME issues for zippier builds.
you could give the nozzle a go, if it still feeds then the extra length is going to help it seal against the feed lips a bit better.
is there a tappet delay chip on the sector? might be worth investing if there isn't as that can help clear up feeding issues.
It is a pretty thick Sorbo. But now the pistons been modified, might as well keep it like that.
Yes there is a bearing inside the piston rather then the Spring guide. The piston I changed out for is slightly lighter then the old one which may make a difference. Before I took it apart there were no PME issues so keeping it like it is might be the better option (That and I am way over my budget!)
No tappet delay, but I have a spare plastic one in my box that I can use!
Not the G&G AR latch - it has been replaced thankfully
(my pic of G&G ARL was invalid so updated the original reply & here again is chunky G&G ARL with nicks)
(the existing aftermarket ARL was perfect as is, no need to buy another for this box btw)
the box still has the G&G metal safety arm though
(nothing wrong with it - just saying the original safety is still there & is perfectly fine btw)
When you try to fit thicker 16awg, especially silicone 16awg the channels are tight
and the channels or gap right behind the ARL is where they can impede its operation a bit (esp on G&G ARL)
SHS pistons don't bind in G&G's and the reg G&G V2's have no rear window
So on the lightened SHS pistons, the boxes like G&G V2's or others is where I only would consider using them
(I'm a bit paranoid about ensuring stability on piston flying back n forth at snappy speed
others might feel I'm being a tart, but window boxes I prefer solid piston guides/runners or near enough for continuous stability at speed or under stress - just me being tarty
So the pistons with rails cut to bits I'd only use in say a G&G v2 or a v3 box myself)
Piston is fine, nice trim on 3rd tooth, 2nd tooth already removed (first is the pickup)
The piston will be fine I'm sure, though coz I'm paranoid about rail support I would have chosen the other lightened one...
install it & there is whisper thin bit of material just over the sector/tappet cam which will retract a bit more...
It can be a bit tight fit, you might have to file very carefully the arc part that meets the axle/spindle in center on some sectors
very little filing, a drop of epoxy might be wise to ensure it stays put perhaps
But I use these types very often as it gives a bit more tappet retraction, though you MUST check if tappet bottoms out on the cylinder head at full retraction - check in top half of gearbox with cylinder/head/tappet/ sector etc....
it can really bottom out if you use a SHS v2 tappet plate with that delayer
If so and the cylinder head can be modded slightly....
see that ridge below nozzle, that little rim, you can carefully file that away on some heads if tappet bottoms out
and together with delayer & SHS v2 tappet,you should attain a bit more retraction if done carefully
to produce max retraction almost, for better feeding
Sand front of tappet slightly to ensure good seal on bucking if required if slightly short/worn nozzle used
Depending on hop unit used, just check if the old nozzle seals on old tappet etc...
offer the hop unit up to gearbox with nozzle tappet at full rest
you should feel the nozzle touching the bucking lips with say 1mm to go before hop is fully rested against the box
so when all pushed home to each other, the nozzle maintains contact/resistance to ensure a seal on bucking lips
It might have had issues feeding like you say, then the nozzle was filed, but might have lost some seal/fps coz of it
Really should have used a delayer and/or SHS tappet as the aftermarket (G&G's tend to be black) tappet might have retracted less
Though as explained when using that delayer AND SHS tappet it will very likely bottom out as there is a lot more retraction
So when trying to obtain/improve nozzle travel/retraction you really need to check thoroughly in top half of box
(If done properly, it will feed well even on crappy weak spring mags - well as best as can be on shit mags, but improve feeding x 10)
The nozzle that is in there might be OK but might only just touch the bucking lips
I'd be tempted to sand the front of red tappet plate a bit to get the nozzle tappet to return forward a bit more
hopefully ensuring a better seal on bucking lips that "might" have been lost if nozzle was filed due to feed issues
I mean fuck all to lose and if goes a bit crappy then just buy a SHS tappet
You don't wanna go nutz and splash out loads of bits, but you had a touch on gears
Not a bad result, got some nice bits already to play with
The G&P M120 armature would go nice in a neo can
so at some point if an old neo motor croaks, pull out the knackered aramture, plop in the G&P one
should have a similar spec SHS/RA 16tpa neo motor to add some zest to a M4 or long motor build
If you got access to a quick change spring gun....
Test the spring in there and not the fps - even on a comparison scale than gospel fps
note the fps and/or the increase over the QC guns regular spring say 15% on fps
then decide if you might say sod it & Short Stroke the sector a couple of teeth
so that it fires at about 340fps one it is all assembled and running correctly
The cylinder - should have been a G&G blue steel one usually not brass
where is the port in relation to barrel length to ensure it is about correct volume ???
Not the G&G AR latch - it has been replaced thankfully
(my pic of G&G ARL was invalid so updated the original reply & here again is chunky G&G ARL with nicks)
(the existing aftermarket ARL was perfect as is, no need to buy another for this box btw)
the box still has the G&G metal safety arm though
(nothing wrong with it - just saying the original safety is still there & is perfectly fine btw)
When you try to fit thicker 16awg, especially silicone 16awg the channels are tight
and the channels or gap right behind the ARL is where they can impede its operation a bit (esp on G&G ARL)
SHS pistons don't bind in G&G's and the reg G&G V2's have no rear window
So on the lightened SHS pistons, the boxes like G&G V2's or others is where I only would consider using them
(I'm a bit paranoid about ensuring stability on piston flying back n forth at snappy speed
others might feel I'm being a tart, but window boxes I prefer solid piston guides/runners or near enough for continuous stability at speed or under stress - just me being tarty
So the pistons with rails cut to bits I'd only use in say a G&G v2 or a v3 box myself)
Piston is fine, nice trim on 3rd tooth, 2nd tooth already removed (first is the pickup)
The piston will be fine I'm sure, though coz I'm paranoid about rail support I would have chosen the other lightened one...
install it & there is whisper thin bit of material just over the sector/tappet cam which will retract a bit more...
It can be a bit tight fit, you might have to file very carefully the arc part that meets the axle/spindle in center on some sectors
very little filing, a drop of epoxy might be wise to ensure it stays put perhaps
But I use these types very often as it gives a bit more tappet retraction, though you MUST check if tappet bottoms out on the cylinder head at full retraction - check in top half of gearbox with cylinder/head/tappet/ sector etc....
it can really bottom out if you use a SHS v2 tappet plate with that delayer
If so and the cylinder head can be modded slightly....
see that ridge below nozzle, that little rim, you can carefully file that away on some heads if tappet bottoms out
and together with delayer & SHS v2 tappet,you should attain a bit more retraction if done carefully
to produce max retraction almost, for better feeding
Sand front of tappet slightly to ensure good seal on bucking if required if slightly short/worn nozzle used
Depending on hop unit used, just check if the old nozzle seals on old tappet etc...
offer the hop unit up to gearbox with nozzle tappet at full rest
you should feel the nozzle touching the bucking lips with say 1mm to go before hop is fully rested against the box
so when all pushed home to each other, the nozzle maintains contact/resistance to ensure a seal on bucking lips
It might have had issues feeding like you say, then the nozzle was filed, but might have lost some seal/fps coz of it
Really should have used a delayer and/or SHS tappet as the aftermarket (G&G's tend to be black) tappet might have retracted less
Though as explained when using that delayer AND SHS tappet it will very likely bottom out as there is a lot more retraction
So when trying to obtain/improve nozzle travel/retraction you really need to check thoroughly in top half of box
(If done properly, it will feed well even on crappy weak spring mags - well as best as can be on shit mags, but improve feeding x 10)
The nozzle that is in there might be OK but might only just touch the bucking lips
I'd be tempted to sand the front of red tappet plate a bit to get the nozzle tappet to return forward a bit more
hopefully ensuring a better seal on bucking lips that "might" have been lost if nozzle was filed due to feed issues
I mean fuck all to lose and if goes a bit crappy then just buy a SHS tappet
You don't wanna go nutz and splash out loads of bits, but you had a touch on gears
Not a bad result, got some nice bits already to play with
The G&P M120 armature would go nice in a neo can
so at some point if an old neo motor croaks, pull out the knackered aramture, plop in the G&P one
should have a similar spec SHS/RA 16tpa neo motor to add some zest to a M4 or long motor build
If you got access to a quick change spring gun....
Test the spring in there and not the fps - even on a comparison scale than gospel fps
note the fps and/or the increase over the QC guns regular spring say 15% on fps
then decide if you might say sod it & Short Stroke the sector a couple of teeth
so that it fires at about 340fps one it is all assembled and running correctly
The cylinder - should have been a G&G blue steel one usually not brass
where is the port in relation to barrel length to ensure it is about correct volume ???
So I spent the best part of 10 hours sweet talking this blasted thing.
Whoever worked on this box before stripped out so many screws in the pistol grip. It's been a nightmare. I really wish this was a Quick change spring gearbox.
The gears are definitely SHS as they are branded as such. Inner barrel is 433mm long so have stuck with the full brass cylinder.
I used the new AR latch (Because why not). Checked shimming etc.
I rewired for a mosfet, taking your advice and shoving the motor wires down the back of the pistol grip. I had to mill away at parts of the gearbox just to get the 22AWG low enough for the bevel not to eat away at them, I did try the superglue/shrink method. But ended up with plastic all over the inside of the gearbox. In the end I just have them loose and seem to be doing better. I stuck with 18AWG wire as I cant really mill out enough of the box to fit 16AWG without severe compromises. Not got the funds for silver wire at the moment either!
Put the gearbox back together with a fairly light spring. It was firing at 300 FPS. Went back into the box and managed to strip some of the trigger wiring, had to redo that. Put new spring in and now up to 370 FPS! Stripped it down again and put in a spring that managed 330 FPS.
I installed the SHS Hop unit I bought, I dremelled out the fixed plastic nub and created a new curvy bit for a nub to go in , it really struggled to feed well so put in the hop unit that came with it and changed the new arm into it. I installed a Prommy Purple and did a range test. I felt that it wasnt quite hopping .30's well enough for me, so I tried a Modify flat hop kit. The bucking was very loose around the barrel and I lost about 30 FPS and went down to 300. I struggled around with that for a bit, went back to the Prommy purple and kept the Modify flat hop nub in. Back up to 327FPS. No idea on range or accuracy as in theory a flat hop nub and standard Prommy bucking shouldn't work, but it is giving me more of a hop effect then the usual nub. Hopefully will do a range and accuracy test soon.
if it doesn't work out I do have some Prommy straight bucking that I can try, but not sure the nub can put enough pressure on it. Both hop unit arms I have are pretty meh.
I put about 2000 rounds through the M16 and the gearbox seems to be holding up internally. I am getting some feeding issues using High Caps, but likely just not able to feed quickly enough and causing jams. With my PTS Midcaps all is well.
If I have to go into the gearbox again though I am just going to get a Quick Change gearbox and start over. The current gearbox, whilst well built is a real pain due to the tight wiring channels, stripped screw holes and the gearbox screws being on the wrong side.
