Losing FPS rapidly...

[nicholas-c]

Hey guys, If you remember I did upgrades to my KWA SR10 a little while ago... 6.01mm Tightbore and M90 spring, It chrono'd at around 345-355FPS right on the border of site limits. 2 weeks after that it was around 330-340FPS, thought nothing of it. 2 weeks ago it was chronoing at 310-320... But I wasn't playing that much more marshal training than anything else. However sunday just gone I chrono'd in the morning to check up on my baby and it was 300... 295... 297... Huh... Lunchtime I took out my barrel and cleaned it took hop-up off completely and it was 270ish... Checked I put it back properly... 260... 250... 240... The last chrono I did was around 230 so in one day i lost 60 FPS or so... Didn't really affect range much since its epic anyway but... Yeah... Something isn't right?

TL;DR My FPS has gone from 350FPS down to 230 or so in the last 2-3 months... 60 of which was on sunday

 

[bigshep]

Spring snapped? Happened in one of my guns, was 320, then dropped to 270 odd, range was still ok, just fps waay down, turned out it had snapped a coil on the spring

 

[Airsoft-Ed]

Either your spring is damaged in some immense way, the air seal on your piston head is dodgy or the rubber seals are broken, or your piston is stripping teeth one by one causing an fps drop every time one breaks off.

Though I'd have thought you'd get some more general cycling issues if that were the case. Wouldn't have thought that'd ever happen on a KWA either.

If it's not any of those things, I can't explain it.

 

[Liam Porter]

It could be that your spring has snapped. My step-dad's spring did, it literally shattered, it snapped at every coil apart from the last 5 or 6, by that point, there wasn't enough power to even push the BB past the hop.

Could also be a seal that's been trapped/caught when you put it together, which has then ripped more and more with usage.

Another possibility is if teeth are being broken from the piston one by one, meaning the spring is pulled back slightly less each time one's removed.

 

[joshcowin]

another one who had a spring snap into 2 pieces and it dropped to 245 fps,it could be that the piston has had its teeth worn down and its now missing one so its not pulling it the last part.to test for compression or if you have a seal gone,hold your finger on the loading nozzle and push the spring release if it goes straight forward its a air seal problem,if it goes forward slowly its something else

 

[Sgtash]

could also be a broken cylinder head nozzle have seen that on a v3 box gave the same issues as your having

If you want rid I will buy the Sr10 off you

 

[nicholas-c]

lol Once I get it up and running properly I may sell it as it's a good gun and I like to have a project