Upgrading my M15A4

[Kruc1fix]

Im looking into buying a new hop up unit, spring, piston, and piston head.
My current set up is

Internals-
G&P Piston
Madbull M110
Systems Bearing spring guide
JB Unicorn TBB


-I'm going with King Arms Metal Hop up.
http://www.airsoftgi.com/product_info.p ... ts_id=2639

I also need to get a bucking. I've heard that Prometheus would be my best choice but whats the difference between Hard and Soft?

-I also want to upgrade to a Systema M120
http://www.airsoftgi.com/product_info.p ... cts_id=121

-And a new piston, G&P (White Color)
http://www.airsoftgi.com/product_info.p ... ts_id=1636

For these upgrades will I need a Better gear set than the stock M15A4? Also, would I need a "Silent" piston head to help relieve some stress from the m120?

Any recommendations?

[devildog16]

I've got a CA M15a4 as well and have asked these questoins before.  The stock gears should be fine if you take care of them and grease them properly but remember that there going to take more use and wear out faster, your call really. Just observe the gears more closely.  With a 120 i dont think you'll need a silent piston head.  I've heard both ways but I dont think It'll be a problem.  (I run a 120 fine without one)Dont quote me on this but the difference between hard and soft buckings is that the hard bucking doesnt need to be winded as much to get hop were as the soft need to be winded more.  

Hope this helps but wait for more input before you act to get more expeirenced opinions.

bryce

[thatoneguy92088]

I just got a King arms hopup on my CA m15. So far it feeds fine and the hop works great. The metal seems to not be super precise and getting the screws in was tough so be sure to baby them so you don't strip the screws. My m15 has had a PDI 170 spring (similar to m120) in it for 4 years and the gears are perfectly fine. I have gone through two hopups before this one, but my gearbox has been fine for all those years.

[Kruc1fix]

how long would you say a spring lasts before you should replace it?

[Ganef]

There isnt really a set time. I run mine until failure, because by the time you notice a drop in fps it may be cracked already. Be careful with those silent piston heads, make sure you put some locktight on it or it may come off of your piston and be smashed by the spring. I have seen that happen twice.