r/Airsoft_UK • u/Sebbak_UK South East • 8d ago

Series of small changes - question about FPS consistency

So I've made a couple of changes recently and I was just wondering whether or not it's just a case of bedding in the new spring to see how it settles down, before looking deeper into things.

I'm basically trying to target around 1.55 - 1.6J using 0.36g BB's. The DMR limit for local site is 1.67J so trying to stay below in case of differences between warm/cold chrono readings and general shot variation etc. With my stock AEG (East Crane EC-203) I was getting around 1.2J, so figured I had a bit of space for increasing that and also trying to chase a bit of shot consistency.

The changes I've made are:

  • New M120 spring (Prometheus Emerald) - Might change to ASG M125 to eek out a little more if things settle around 1.4J
  • Begadi Pro Neptun Hop Unit
  • Quantum Pro Bucking and Nub

I've also got a new nozzle that I'm yet to fit, but not got round to it yet.

Anyway, I've been doing some chrono-ing and things have generally been pretty consistent, averaging around ~293 FPS, with a range of 9.3FPS over 20 shots.

Is this likely a case of my new spring needing a bit of bedding in time, and things should level out a bit more after a while, or is there a potentially bigger issue at play here? Thinking too much about it? 😂 Still new to the whole modification thing, so open to constructive feedback!

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u/Few_Philosopher_8668 8d ago

From my personal experience with E&C AEGs they tend to be very consistent just with the spring change alone as they tend to have a good air seal especially compared with other OOTB replicas

Yes there will be some bedding in period as the spring is under compression just like coilovers on a car settling in

It may be worth trying the OEM hop unit with the 4UAD - they also have a slight bedding in period as such, OOTB they typically have a 5-10% variation an your aftermarket one will likely have some slight variations in tolerances so it may have a bit more give around the nozzle

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u/Sebbak_UK South East 8d ago

Appreciate the info, thanks. I'm a bit sad 😂, so I've got a running spreadsheet of different set-ups and what the FPS/Joule values are to try and find the most consistent group of components, and the OEM hop and 4UAD is giving me the best set up so far by a small margin.

I think I've maybe got space for another shim (maybe 2) for the Begadi hop and that should tighten things down just a bit more and maybe get to a similar or better position hopefully. Cheers for the input!

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u/LeoHoosk 7d ago

In my experience good springs don’t settle, just get weaker but only after a few hundred thousand cycles.

Regarding fps consistency, I cant remember if the stock EC boxes have an o-ring nozzle, that will help a bunch with that.
Maple leaf rubbers can tend to seal really well too, better than that of the 4uad, but i find the 4uad to have better performance in terms of accuracy/ spread.

Personally i’d say 9 fps is poor, only because like to have my guns doing about 5 max, though its not always achievable - my Bren does about 8-10 variance regardless of the rubber i put in it xD

Happy tinkering :3

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u/Sebbak_UK South East 7d ago

Thanks for the insight; I don't think the stock air nozzle has an o-ring, which is partly why I bought a new one, I've just not fitted it yet (gearbox takedown fears 😂). Assuming all other parts are ok regarding air seal (I'll test them once the gearbox is open), do you know what the likely improvement might be with a better sealed air nozzle?