Upgrades to increase FPS and Range

Hey everyone,
I'm looking to internally upgrade my echo 1 m4. I'm curious to know what parts of the gear box greatly determine how far and how fast a bb will travel. I'm not completely sure if it's the spring, the piston, the barrel, etc. I don't want to replace a perfectly good set of gears with a new set and have nothing done with the performance what so ever.

Thanks,
Mike

It's all a factor. Others will give you the specifics but in general:

Barrel
A longer barrel helps stability (thus accuracy). Too long and it reduces FPS.
Tight bore helps stability and marginally increases FPS (better control of release air pressure). Too tight and the bb's fail.

Motor.
Bigger motor will push a heavier spring and/or increase rate of fire. Too heavy and you may strip your gears.

Spring.
Heavier spring will apply more force to the piston; most direct FPS increase point. Too heavy and your ROF reduces, and may damage your motor.

I think that's correct.

If your looking for range you just want a new barrel.Looks like you have a m4 i would go with a stainless steel 6.03 407mm Its a great barrel for a M4.
Link for the barrel:http://www.airsoftgi.com/product_info.php?products_id=6071
But when you put in the barrel your gonna want a bucking
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And when your upgrading you want to stick with one specific brand internaly.
And when you said you want the bb to fly faster looks like your wanting more fps and that means you want a spring but i would honestly not crack the gearbox unless you absolutely had to
Hope this helped you out somewhat lol.

Upgrade your barrel and hop up. I wouldn't bust open that gearbox unless you have to. "If it isn't broke...don't fix it."

Replace everything!!! Keep nothing stock

Start with a tight bore. Add a good hop up. Upgrade the gears and mech box. Replace the upper and lower with real steel equivalents.
redo the buffer, spring and seals. Add a new outer barrel, no rails. Add iron and optical sights. 13.3 lipo and paint the whole thing purple.

Oh yeah, and dont forget the sling pouch.

Purple is a little far

But the sling pouch is essential.

What wrong with your E1? What exactly are you looking for in your gun? Do you want get 100 yard head shots? Do you want throw out enough BB's they look like a rope spraying out your M4 and you can trim the bushes? There's an easy road to both options: build a DMR or buy a SAW.
Here's is the grail of DMR builds:
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Here's the hedge trimmer:
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Not to tell you what to do with your money; but it might just be easier to save up, get a KWA, Celicus, or Systema, and keep your E1 as a loner gun. What wrong with that E1 again?

He needs to upgrade everything and add that tactical sling pouch.

good point. mustn't forget the ris mounted tactical can opener.