Trimming springs down

[TomFarrington97]

Evening hive mind, I have an SP130 spring that’s putting me around 15ish FPS over the limit on a .2G BB. Would I be able to lose the 15 FPS by trimming the spring down or would I be better off just buying a new one? I’ve never done it before but after watching a video it seems fairly straight forward and I have all the required tools at work, so that is no issue I just wanna know if I’ll get enough of a drop. Cheers. 

[EDcase]

You certainly can but to do it properly is a bit more involved than just cutting and putting back in.

 

Once cut (I think one turn should do) you have to heat the end with a torch and then bend it flat against the next coil.

Then file it so its all as flat as possible.

 

It should look the same as before you cut it.

 

Alternatively for 15fps you could try to leave the spring cocked. (Do a quick trigger pull in auto so it doesn't complete a cycle)

Might have to leave it like that several weeks...

[Sneaky]

You could try cutting a loop off first, then crono your aeg. If you have any issues, just buy a spring.  Springs after a period of time when compressed will settle into a new state, which could potentially work for you.

[EDcase]

Did you set hop for 0.2g ?

Try chrono with hop on and off.

Can make a big difference.

 

Edited September 9, 2021 by EDcase

[TomFarrington97]

17 minutes ago, EDcase said:

You certainly can but to do it properly is a bit more involved than just cutting and putting back in.

 

Once cut (I think one turn should do) you have to heat the end with a torch and then bend it flat against the next coil.

Then file it so its all as flat as possible.

 

It should look the same as before you cut it.

 

Alternatively for 15fps you could try to leave the spring cocked. (Do a quick trigger pull in auto so it doesn't complete a cycle)

Might have to leave it like that several weeks...

Cheers fella! Yeah I realise I have to heat the end and press flat. I work in a workshop so got plenty of tools to do that kinda stuff just wanted to know how much to cut off lol.

 

also yeah tried it with the hop and was still

over even set for .2s but thank you for the help fella I’ll have a tinker tomorrow and worse case I’ll fork out another £10 for a new spring ?

[Adolf Hamster]

before cutting anything, are you running thrust bearings on both the piston and the spring guide?

 

if so you can lose the one in the piston (replace it with a washer) and that'll drop you a few fps.

 

you do want at least one thrust bearing though, and having it on the spring guide saves piston mass.

[ak2m4]

@Adolf Hamster this first, also if it's a new spring run it for 1000 cycles plus 24 hours compressed.  Plus also find out how your regular sites allow you to chrono, hop set or off etc

[Rogerborg]

I'd wonder what limit you're aiming for with a 130 spring.  If it's a DMR build, I'd then wonder why you're chronoing with 0.2g BBs.  If it's because your site chronos with them even for DMRs and snipers, I'd wonder if they have the first clue about Joule creep, then I'd give a sad sigh, and a single tear would trickle down my cheek.

 

But if you're happy that you only need to lose a little energy, I'd just lop off one coil at a time.  No need to over think it, the spring in my DMR was chewed off on site at the chrono table with a pair of rusty pliers, heated (barely) with a cigarette lighter, and had a small file waved at it briefly.  It works fine, so do a better job and it'll work great for you.

 

The other thing you can consider is not cutting it at all. Just heat the end with a torch until it barely glows, and squish the last coil or two flat.

[Adolf Hamster]

50 minutes ago, Rogerborg said:

I'd wonder what limit you're aiming for with a 130 spring.  If it's a DMR build, I'd then wonder why you're chronoing with 0.2g BBs.  If it's because your site chronos with them even for DMRs and snipers, I'd wonder if they have the first clue about Joule creep, then I'd give a sad sigh, and a single tear would trickle down my cheek.

 

tbf, joule creep generally doesn't apply to aeg's, at least in the same sense it's applied to the likes of gbb's, hpa's or bolty's with heavy pistons.

 

that said, i've heard the term applied to meaning the difference between X fps on X weight compared to X fps on Y weight, which isn't the same thing.

 

although i do get the sentiment that a site insisting on the old 0.2g chrono probably hasn't bothered learning the situations when that's not such a good idea.

[Rogerborg]

11 hours ago, Adolf Hamster said:

tbf, joule creep generally doesn't apply to aeg's, at least in the same sense it's applied to the likes of gbb's, hpa's or bolty's with heavy pistons.

 

As a site policy though, it's a poor choice to ignore it.

 

And there was a positive infestation of HPAs and GBBR at my local last week, many of which failed chrono even after doing their speedyboi magic.  Site response: "Oh just run your gun[*] as a DMR then."

 

 

[*] Section 5 firearm!