Spring and Hop Up Questions/Advice For JG M4

[grlichti]

Good Morning Airsofters!

Went to a skirmish this past weekend. Am uber happy with my recent gearbox shim/lube job (Thanks for tips Dominum!). Now my attention is drawn to two items. First, the spring. The gearbox being the "enhanced" JG is all metal incl gears and guides and in the states, boasts an average fps on all the sites of around 400+ fps (120+ mps). But since it is an Italy import gun, it is regulated to start at only 328 fps or 100 mps. Does anyone know what type of spring I would want to change to in order to get to the build strength that comes in same gun elsewhere in world? As I understand it, a 100 spring is roughly 100 mps with .20 (110 is 110 mps, etc). Is this more or less accurate?

Second topic, the Hop Up: How do you feel about changing Hop Up unit to aftermarket (in this case a King Arms)? Is it truly a noticeable and useful upgrade or is it one of those esoteric things that improves only a tiny bit overall performance?

Thanks a lot for the help!

[Jeremy314]

Springs come in a couple varieties. You have your M springs, your SP springs, and your % springs as I call them. I'm not sure what Italy's law are for airsoft and MPS/FPS limits, so make sure you check them before you change anything that can affect that.

The M springs are your M100, M120, M130, etc. The M means Meters (per second) and are rather right on. But you will run into a few oddities. Madbull used to have M springs with the SP punch, but they seem to have sorta that out as both my M110 and M120 from madbull are both right on the dot of FPS they should be.

The SP springs tend pack slightly more punch than the M springs, I'm not sure why though. Guarder's SP springs seem to pack more punch than other SPs I've seen.

The % springs are the 210%, 240%, etc. I don't know much about them honestly. When I first saw them I thought they were for spring powered snipers. The one's I've seen label as % rather than M or SP are usually PDI or Evike's Matrix brand.

As for the hop up, yes a hop up change can make or break your performance. Sometimes all you need is a bucking/nub change, sometimes a full hop up chamber change will do you better. Just be aware that if you change something with the hop up, it could affect compression between the air nozzle of the GB and the hop up chamber. I'll leave the super technical stuff for Dom or Star_Folder to get into, but I figured I'd give you a brief overview.

[Star_folder]

Jeremy's right on all accounts. "%" springs are "%" of a Joule, which is 100%, so a 180% spring should put out 1.8J, or about 400fps with .25s.

I do not suggest changing your hop up chamber. It will require modification, and you highly risk damaging parts of your gearbox getting it to fit. If you want a one piece chamber, you will need to upgrade to a metal body.

Are you able to modify hop up buckings? or just want to buy something that you can drop in for good results?

[grlichti]

Are you able to modify hop up buckings? or just want to buy something that you can drop in for good results?

First, thanks Jeremy and Star_Folder. The hop up unit I was looking at is an all metal complete King Arms unit for the M4. There is also a JG all metal complete unit. Are those not "drop ins"?

As for mods, I am reading with great interest about the "flat hop" mods and that should be something within my "wheelhouse" of tech skills.

That said, would you say that a good quality rubber/nub combo would perform better than stock set up? I was looking at something along the lines of the KWA 2gx rubber, both because it is supposed to be good 'as is', but also because it is one that is recommended for above "flat hop" mods.

Finally, insofar as springs go, further research has got me up to speed on those. Downside, though, is I am very much limited to 100mps/328 fps or more accurately 1 joule in Italy. To upgrade beyond is a felony. Yes, you read that right. So much for THAT idea. Oh well, accuracy rules anyway.

[Star_folder]

The KWA 2GX in it's stock form isn't all that great, but it does make a good flat hop bucking. However, technology has progressed far enough that both Modify and Prometheus make flat hopped buckings if you wish to skip that step. If you want to save some money, try flat hoping the bucking that is currently in the gun.

How does your gun open up when you remove one or two body pins? Does it fold forward like a real M4, or does it slide forward? If it slides forward, that means you have a 1 piece hop up, and you can upgrade it. If it bends, then you have a two piece hop up, and you can't upgrade it. But, don't worry much about it. Hop up units don't have a very large effect on the accuracy of your system. They are simply there to hold everything in place. Sure, some hop up units do it better than others, but I've not encountered a unit that can't be modified to be as secure or accurate as top of the line hop up units.