Can A JG M4 Gearbox withstand a madbull m120?

[RadioMan]

Hi, I own a JG M4 and I realized that it was a pretty bad gun, compared to the other people's gun's I play with. So I decided to upgrade my M4, and change it into an SPR. I bought several things, such as new hop-up, a tightbore barrel, a scope, etc.

But, I also bought a Mad Bull M120 Spring, to upgrade my FPS to around 400. But now that I think of it... Will my M4's gearbox break under the force of the new spring? If so, what can I buy to make my gearbox withstand it?

[Qlong]

Some stock JG already shoot above 400, such as their 416, it'd be best to relube, reshim your mechbox and shove a sorbo pad in there. I had a 416 before with around 5000 bbs through it with no problems.

[TokyoSeven]

Interesting questions. It is quiet possible your mechbox would survive that FPS

Do you know the current FPS of your gun? Jing Gong guns are more often than not already somewhere in the 350-400FPS area. Its quiet possible to install an m120 to achieve the FPS you wish, if you decide to do so please also take into consideration that it would be wise to install a quality bearing spring guide and some good quality metal bushings if not already present and a reshimming,thats just the absolute bare minimum. The is definately more you can do. However Im not going to muck about explaining what parts to get and what not. I would like to jump back to the possibility that your gun may already possibly be near the 400 FPS area.

Lets say for example your current spring yields 370 FPS. Why not just simple install a new quality hop up system and a tightbore barrel. That alone will get your closer to your goal if not achieving it all together. Its possible to swap out other internals to achieve your goal FPS as well. Replacing anything related to the compression system of the mechbox with an upgraded quality part will boost your FPS as well. With the installation of new quality durable parts you should have no worries about the longevity of your mechbox. Do your best to try and keep all the parts by one company if you can, its usually best to do so since a company usually would make its parts to work efficiently together. Mix and matching multiple companies parts can work however you then increase the possibility of failure due to increased differences in companies tolerances when it comes to sizes. As long as all parts are installed properly you should have no issues.

Edit:

If I may I would like to recommened two other companies for springs if you are open to suggestions.
Either prometheus or modify, both are excellent quality companies and both companies produce excellent consistent springs that will stay consistent over time.

[RadioMan]

Well, I actually have the JG Thundermaul, which supposedly had 350 FPS with .2's. But I heard the JG Thundermaul is the same as the JG M4.

[Crunchmeister]

I've chronied several JG M4s so far, and they're all in the 360-370 fps range. Add metal bushings, a bearing spring guide, a new hopup rubber, a bearing piston head, and a 6.03 tightbore, and you're going to be hovering in the 380-390 range, which is more than enough for any outdoor game. 400 fps isn't the target, it's the limit. And with an M120 plus other uprades, you're going to be over the 400 mark.

[dpvu]

That's going to be tough on any mechbox. Run the JG one (making the modifications Qlong suggested) until it breaks. I'm also building an SPR and using a stock JG mechbox, re-shimming, re-lubing and adding a sorbo cylinder head to it.

[RadioMan]

Ok, I've concluded that I'll just not use the spring, but I'll upgrade other areas of the gearbox to make up for it. With the following upgrades will i be around 400 FPS?
-Mad Bull 6.03 Tightbore barrel
-G&P M4/M16 Hop-up Unit
-Modify Bearing Spring Guide - V2
-Modify 6mm Stainless Steel Bushings - Double Oil Channel
-MASK Pro Cylinder Head V2

Those will all fit in my gun correct?
And while trying to install the tightbore barrel on my own, I failed and bent the wire shield a bit. Will that cause my gun to break down in anyway?
And with these upgrades, I should have the range (if not more) of a stock JG M16 right?

Thank you so much!

[TokyoSeven]

You did not state the legnth of the tightbore, but regardless of that for all intensive purposes Im sure that with those upgrades you should be on target if not actually over your goal and if possible you should consider getting an alternate hopup rubber for the hopup as well. I was going to recommened a guarder clear but since your in and over the 400FPS limit...I would suggest something in firefly selection. Just a quick note on inner barrels. Depending on what legnth of inner barrel you aquire you may need to purchase a boreup kit with it as well. You should be fine with anything under a 455mm if you do not wish to purchase a bore up kit.

So you bent the wire shield? Toss the gun out its ruined. Im kidding, I cannot imagine any issues that could arise from bending it slightly. Its purpose is to simply just guide the wires forward and keep them neat and together.

[Bissa]

if the gearbox is the same as a JG416 that yes it will handle it fine, i have an M120S in my 416 with no changes to the gearbox, i have put about 10-15k .25s through it now.

[RadioMan]

Should I get a bore up kit just to be safe? Because my barrel is exactly 455mm. And you scared the shit out of me about the wire shield thing, but I'm glad it will be ok.

[NoGear]

im realy interested in what ur gun looks like after this as i to have a thundermaul. the question is how come ur gun isn't as good as ur friends? are they over the 400 fps limit?

just on a persona matter i would want to install a tightbore as well. boreup kit?

remember ur gun is only as good as you are

[yuhaoyang]

Isn't it possible to skip the bore-up kit and just go with a non-ported cylinder? (sorry for thread jack)

[RadioMan]

NoGear-
The only reason my friends guns were better because they out range me, and my bb's traveled so slow that my friends had time to duck down, or move out of the way, when they heard me shoot. My gun wont look like the Thundermaul when its done. I'm trying to get Mr. Hitman's SPR Mod 0 Mk12 look. Here is the link: www.airsoftcanada.com/showthread.php?t=63331

Yuhaoyang-
Haha, I don't care about the tread jack... As long as my gun works in the end.

[NoGear]

Originally Posted by RadioMan

NoGear-
The only reason my friends guns were better because they out range me, and my bb's traveled so slow that my friends had time to duck down, or move out of the way, when they heard me shoot. My gun wont look like the Thundermaul when its done. I'm trying to get Mr. Hitman's SPR Mod 0 Mk12 look. Here is the link: www.airsoftcanada.com/showthread.php?t=63331

Yuhaoyang-
Haha, I don't care about the tread jack... As long as my gun works in the end.

so ur friends have over 400 fps? the m4 should be ready for actual games right out the box cqb-field. Could it be that ur trying to over range ur gun or are you actually shooting within the mid margine of ur actual range

[dpvu]

A bore-up shouldn't be needed until you're past the M16 barrel length (509mm) if I remember correctly.