Downgrading a King Arms M4 FPS to 350ish

[Amberclad]

Hi I was wondering how could I downgrade my KA M4 who has 440 FPS , i Need it to 350 for CQB , I have read to change the spring but with what other spring ????

[ThunderCactus]

prometheus ms100 would get it right to 340fps

[Scopedog]

Springs are generally rated in m/s (meters per second). So an M100 or S100 spring would be 100mps or roughly 328fps.

Other components in the mechbox, inner barrel, hop-up, and quality of your air seal are going to influence velocity. Use the spring ratings as a ballpark estimate, not an absolute value.

[Amberclad]

Alright so springs should be the first thing to change ?

[Styrak]

The spring.

[Kozzie]

No not springs.... the spring. The spring is the only thing you need to change in order to lower the FPS, unless you want really shitty compression.

But You should already know that. Because you were already given all of the information you need in your last thread. ** ASC Thread ** Did you even bother doing any research or reading what people wrote?

Open your mouth sweet pea, here comes the spoon

1) Copy this: how to change spring version 2 gearbox
2) Click this: youtube.com
3) Paste in the search bar, hit enter and persto, you're a big boy now.

If it seems too difficult search for a gun dock on this forum or bring it into an airsoft shop in your home town.

[L473ncy]

Hell if it's going to be a CQB only gun go with M80 or M90. Less stress on the parts and travels just as fast/well in CQB environments where the difference between 270 FPS and 350 FPS is close to nothing (hundreths of a millisecond based on some calculations that I did a few years ago at 20-30 ft engagement distances).

[Amberclad]

Kozzie my question is what kind of springs , I have read about it , I seek advices from multiple sources before doing somethings. If you don't want to answer then its your choice . For Latency , I don't know if I understand well CQB but I see it as indoor play or outside play but as being '' Assault '' player .

[Styrak]

He answered your question. THE spring. The mainspring.

[JonsM4]

The "Spring"

Not "Springs".

Modify S100 AEG Upgrade Spring will be around 340fps with .20 bb.

[Deadpool]

Maybe you should pay a gundoc to do it.

[HackD]

Originally Posted by Amberclad

Kozzie my question is what kind of springs , I have read about it , I seek advices from multiple sources before doing somethings. If you don't want to answer then its your choice . For Latency , I don't know if I understand well CQB but I see it as indoor play or outside play but as being '' Assault '' player .

Close Quarters Battle. Meaning in a relatively short, close-in engagement distance, requires a Minimum Engagement Distance limitation of FPS on the gun being used... any closer than that - in any environment, and it don't matter what spring you have in your gun, the 350 fps spring or the 'stock' 440 fps spring, you aren't going to be shooting.

No matter what the environment, whether CQB type environments where MED's are short, or in the field, where distances can be longer, the safe spring rate for AEG's are considered to be in the 350-400 fps range, and under 350 fps for indoors work.

Before asking further questions i advise you watch this video on youtube. At 20 seconds in, you can clearly see the spring that kozzie, myself and others have referred to. King Arms Gearbox - YouTube


/end spoon-feeding.

[Amberclad]

Sorry I think you guys misunderstood me , I knew wich spring to change (the main one) and I have watched videos to how to change it , my concern was to change to a what M100? M110? i guess not M110 since in this video King Arms Gearbox - YouTube it says its M110 and the website where I am going to buy says the FPS is 420 ish to 440 ish. Sorry if I formulate badly my questions , English is not my primary language.

[JEEPEE]

Celui-ci devrait faire l'affaire

http://www.airsoftparts.ca/store2/in...roducts_id=884

[m102404]

Buy a 100% or M90 spring if you want to be sure you're going to be under 350fps. i.e. Modify S90.

A 110% or M100 spring will probably be ok...but you might be just over.

Don't worry too much about the lables...different manufacturers use different notations. Some are rated based on Meters/Second (multiply by 3.3 to get FPS). Others are rated on % of 290-300fps (which is the "TM stock speed"). So a M100 = 330fps...a 100%=290-300...a 110%=320fps...etc...

The numbers are going to be off depending on your specific setup...how complete the airseal is...other parts that "boost" the FPS a bit (i.e. bearing spring guides/piston heads...tight bore barrels...etc)

So if you want to hedge your bets...go with 1 power level down from the theoretical.

And...the ONLY way to actually know is to use a chronograph.

Hope that helps.

Airsoftparts.ca has all the parts....tell Jugglez you want a Modify S90+ spring...tight pack of coils go at the spring guide end.