Upgrading a JG M4A1

[Poison Muffin]

Hi everyone.
I'm still a newbie in airsoft, and I'd like to upgrade my gun in the near future. Since I don't know much beyond how an AEG works, I wanted some advice as to what I should upgrade.

My AEG is fairly new. Got it two months ago, and it's still fine. Does around 400 FPS and all. I'm planning to upgrade it in a few months, since I figured it'll need some work by then, so I wanted to get started on what I should get and what's it gonna cost me.

I was thinking about rebuilding it from the ground up, and get rid of all the cheap Chinese parts. What do you recommend?

Also, a totally unrelated question. I suppose it fits the accessories forum more, but I didn't want to start threads needlessly.
Will a King Arms CASV fit on my JG M4?

[Conker]

If you don't know much, don't touch the internals, at least until something breaks. JG are not top of the line, but they're still quite good (especially their more recent versions). They're probably the best chinese brand.

Yeah, the KA CASV should fit and you probably would be able to install it quite easily.

[Poison Muffin]

Of course. I have no intention of accidentally breaking it if it still works. But it will break down eventually, so I'd rather be ready with the parts to rebuild it.

So, what do you recommend I put in there when the time comes? Reliability will come from high quality parts, I suppose, but I'd also like to keep at at 400-430 fps.

[theguy]

400 FPS is over most feild limits here, plus, thats really far more FPS then you need.

to keeep it running well?

shims, lube, and a softer spring.

but Comanche has it right, is nothings wrong with it, and you don't know what your doing, don't open it

[yuhaoyang]

systema M120 complete mechbox with a systema magnum motor, prometheus 6.03 inner barrel with prometheus 1 piece hop-up and rubber sleeve, new prometheus piston to put in the systema(get a gun doc, it takes 5 minutes), I would say madbull JP adjustable front end, a KA/CA/magpul reciever, a KA/magpul stock, and a magpul MIAD grip. done. lawl, it will cost a lot though, and it would take maybe an hour-hour and a half to put it all together.

[theguy]

Lmao, or you could do that :P

[yuhaoyang]

hey, he said he wanted to get rid of every single ACM part from his gun eventually =p

[lemegacool]

Originally Posted by Poison Muffin

Of course. I have no intention of accidentally breaking it if it still works. But it will break down eventually, so I'd rather be ready with the parts to rebuild it.

So, what do you recommend I put in there when the time comes? Reliability will come from high quality parts, I suppose, but I'd also like to keep at at 400-430 fps.

400-430 is WAY too high for gaming and for your poor v2 shell... yes reliability will come with quality part but also with proper installation (shimming) and reasonnable fps... for the velocity you will be looking for around 360-380 MAX (ballisitc wise), my primary outdoor gun currently shoots 350-360 fps and it's shooting very far with .28g bb's

or you could buy a cnc v2 shell and run it pointlessly at 430 fps...

[Poison Muffin]

I live in Israel, and we kinda have different limits
CQB limit is 400. For an open area, 460 for automatic rifles. Bolt action rifles can go up to 600.

The tax rates here are pretty high, plus there's only one legit place to get Airsoft, and they take an additional 60% to themselves (after tax and shipment fees).
My $130 AEG cost me a little less than $400, and it's considered a cheap gun. So buying parts online would be a lot cheaper than a new AEG (Especially if it's higher quality - TM costs double).

Thank you for the list of parts! I have a few questions though:
1) Are the external modifications really necessary? Why do I need a stock and a grip to upgrade internal parts? Also, both receivers are metal. Is there a reason to get new ones?
2) The Systema mechbox is quite pricey, and I'd like to cut my expenses a bit if possible. Would it be cheaper to buy the parts separately? If so, what should I get?
3) How can I achieve consistency in FPS during automatic fire? I heard it has something to do with the cylinder, but I'm not sure what's that all about.

On the side note, I have no intention of opening up the gun until I absolutely have to. I'm just making preparations for the future because the day will come when it'll break.
I do know people who can upgrade the gun for me, but I'd like to learn to do this myself some day.

Also, could you please be a little less cynical?

[Styrak]

Originally Posted by yuhaoyang

systema M120 complete mechbox with a systema magnum motor, prometheus 6.03 inner barrel with prometheus 1 piece hop-up and rubber sleeve, new prometheus piston to put in the systema(get a gun doc, it takes 5 minutes), I would say madbull JP adjustable front end, a KA/CA/magpul reciever, a KA/magpul stock, and a magpul MIAD grip. done. lawl, it will cost a lot though, and it would take maybe an hour-hour and a half to put it all together.

That costs like twice as much as his gun does. He definitely doesn't need a complete systema mechbox.

Poison, does it work fine right now? If so, why do you want to change it? Buying parts just for the sake of buying parts is dumb.

[yuhaoyang]

if your on a budget you can go a lot cheaper. Try a ajax STS with your current set-up, and just order from redwolf what ever parts break in your mechbox. Some of the JGs I've seen have CA gears, which should be perfectly fine, the things that are likely to break are just the bushings, and maybe the piston is a bit too weak for 400 fps, reguardless, they are pretty cheap. Your choice if you want to upgrade the hop-up to a prometheus rubber and a 6.03 madbull V2 inner barrel for consistancy's sake. Also, if your gun runs on nylon bushings it's strongly recommended that you replaced them as soon as it is possible.

Canadian prices are about 2x US prices as well, don't worry about it =p

and it seems like I misread your posts, sorry. I had thought you wanted to eventually replace everything on your gun lawl.

[spaceman13]

For fps consistency some guns run better with lower fps.Good accuracy is key in airsoft.I would suggest a softer spring as mentioned before,tightbore and a good hop up rubber.If you already have a metal body don't bother changing it.A broken upgraded high fps gun is worthless in the field.Oh yeah,the best upgrade is a good charger and battery.

[Poison Muffin]

First of all, thank you for your help!

Now, I am not on a budget, I'm just asking if it can be done cheaper
From what I can tell, the super duper upgrade yuhaoyang offered would still cost me less than a new JG, and JGs are very cheap around here.

So, if I upgrade the bushings (I have no idea what kind I have in there right now) and piston is should keep running? What about the gears? Wouldn't they get worn down, especially if they're cheap Chinese ones?

Another problem I have is trigger response time. When firing rapidly on semi auto the gun tends to jam. It sounds like the gear doesn't do a full cycle before I let go of the trigger, and I gotta switch to auto to unjam it. How can I fix this? I want to be able to use semi :P

Also, a question about barrels: Why does everyone use the 6.03? Why not put a 6.01 in there? Wouldn't it be more accurate with a tighter barrel? I know only one person who has a 6.01 and his AEG is a friggin monster. :O

[yuhaoyang]

HA!
they wouldn't... trust me they wouldn't lol...
XYT gears are made of some cheap untreated steel, and the lemon rate is apparently high, I'm not sure if JG mechboxes use CA or XYT gears. CA are of a good quality and will last a long time.
It shouldn't "jam" on semi, if it stops cycling, just pull the trigger again on semi to fire. You can fix this by fixing your trigger finger habits, getting a larger battery, or even a better motor or torque up gears, although that's nearly pointless, just to fix trigger lag, and expensive.
a 6.01 has very specific BBs that it likes; 6.03s can accept almost all brands of BBs, and the consistancy isn't all that bad IMO.
Everything else inside the gun besides the nylon bushings and the piston should be fine; although I really would recommend an AJAX STS system, or a ARS MASK piston and cylinder head. it's I think $45 USD for the AJAX, and $45 for the MASK sorbo stuff, I strongly suspect that the AJAX would do a much better job, but the MASK set helps reduce firing noise (it also requires the removal of the second tooth on the piston); both help reduce mechbox shell stress greatly. Of course, you can use both together.
If you really really are not on a budget at all, you might as well get the Systema M120 from redwolf lol.

[Poison Muffin]

Just calculated it:
Systema magnum motor - $89.00
Systema M120 complete mechbox - $229.00
Prometheus 6.03 inner barrel - $53.99
Prometheus 1 piece hop-up and rubber sleeve - $9.99
Prometheus piston - $29.99

That's $412. My cheap ass JG cost me $380.95. (Btw, why change the piston that comes with the Systema?)
I don't want to spend so much money if it can be avoided with a few dollars for bushings, piston and the STS thing, but I'm wondering how beneficial it will be for the long run. I'll have to replace more and more parts over time as they wear down, so I'm wondering if that will cost me more?

The trigger thing isn't really an issue, it just sucks that I can't use semi. I'm not going to waste money just for that.

Also, what do I do with this Ajax STS thing? Google says it's supposed to put pressure on the front of the mechbox and it prevents it from breaking. That's great, but just out of curiosity, what does it actually do?