Jump to content

Welcome to Airsoft Forums UK
Register now to gain access to all of our features. Once registered and logged in, you will be able to create topics, post replies to existing threads, give reputation to your fellow members, get your own private messenger, post status updates, manage your profile and so much more. If you already have an account, login here - otherwise create an account for free today!
Photo

Varying FPS?


  • Please log in to reply
12 replies to this topic

#1
Indieboi918

Indieboi918

    AF-UK Starter

  • Members
  • PipPip
  • 56 posts

  • Guns: Two Tone KWA KG36C
    TM M3 Benelli Super 90 (TT Blue)

  • Loadouts: Soldier '95 Camo
    CoverT 1/2 Finger Gloves
    British Army Assault Boots
3 Weeks ago I took my gun to an Airsoft shop and had it chrono'd it came out at about 340FPS

2 Weeks ago I took it to my site for it's first game and it chrono'd at about 335FPS at the site.

Today I took it back to the same site to play again... the first shot was at 351 FPS (only 1 over the limit) 2nd shot was at 360, the highest I'd ever seen this gun chrono, so I had to hire a gun for the day.

what I want to know is how is it possible for the gun to be at 335 and then 2 weeks later be at 360?

Looks like i'll be getting a weaker spring.

Thanks,
Steve

#2
JerseyRider

JerseyRider

    AF-UK Addict

  • Members
  • PipPipPipPipPip
  • 1290 posts

  • Guns: JG M4 S-system
    JG M4 CQB
    CYMA Glock 18C

  • Loadouts: British DPM's
    Warrior R.I.C.A.S Compact (OD)
What make is it?

#3
Indieboi918

Indieboi918

    AF-UK Starter

  • Members
  • PipPip
  • 56 posts

  • Guns: Two Tone KWA KG36C
    TM M3 Benelli Super 90 (TT Blue)

  • Loadouts: Soldier '95 Camo
    CoverT 1/2 Finger Gloves
    British Army Assault Boots
<<< KWA it's a KG36C

#4
Devastator

Devastator

    Admin

  • Root Admin
  • PipPipPipPipPip
  • 4298 posts
How many rounds have you put through it? Also did they have a different chrono at the site? I wouldn't like to think different chrono's would vary that much but I guess you never know..

#5
B00ts

B00ts

    AF-UK Newbie

  • Members
  • Pip
  • 16 posts

  • Guns: 2 star m4
    glock 18c
    Deagle
yeah chronos vary alot,

different makes different tolerences
Never underestimate the power of stupid people in large groups

#6
Indieboi918

Indieboi918

    AF-UK Starter

  • Members
  • PipPip
  • 56 posts

  • Guns: Two Tone KWA KG36C
    TM M3 Benelli Super 90 (TT Blue)

  • Loadouts: Soldier '95 Camo
    CoverT 1/2 Finger Gloves
    British Army Assault Boots
It's a pretty new gun so only about 2-3 470 round hicaps & i'm not too sure if they used a different chrono at the site, didn't pay much attention to it but it looked pretty much the same (bright blue all over).

#7
Hubert

Hubert

    AF-UK Veteran

  • Members
  • PipPipPipPip
  • 646 posts

  • Guns: Currently playing with:
    Walther PPK & P99 with suppressor, SIG-Sauer P228
    W.E. L85 & SUSAT

  • Loadouts: FBI/ NYPD Detective.
    Generic soldier 2007+
It is actually possible that it is the gun, and not the chrono.

There is a reason why G&G put a spring release on their L85 series (and now their newer G&G FN F2000 series).
The piston in a gun has numerous positions. These change everytime the gun fires, as the gearbox cycles - and vary from compact and in, all the way to fully out. If you finish firing the gun whilst it is at the compact position - it will keep the spring in the compressed.

The next time you fire the gun (days/weeks/months) - if you haven't fired the gun since the last time - the FPS will have changed. (I found that it usually goes up if the spring is compressed) The longer the spring is compressed, the higher the FPS can become (This is from my experiences - others may differ)
The spring release on G&G models allows the piston to move to its loosest setting, allowing the spring to extend to an uncompressed length. This keeps pressure off.
For those guns without a spring release (i.e. practically all of them) there is a way to solve this (where the piston and spring are) however, I cannot remember what it is - I think it is shooting until the spring is at the correct setting.

Another reason relating to the gun (I've only ever seen this on the Army Armaments R85, so could only be related to that) is that the way the gearbox cycles could be doing it. My old R85's chrono'ing was always a laugh (when it worked fine) in that few readings were ever the same. The gearbox would start at a low FPS (lowest 295) and slowly rise up to about 370 fps - then drop back down to the low 295-300fps, and slowly rise back up to 370. This cycle woudld take about 15 shots.

Again, it could be the chrono. My old R85 once registered as 0000fps, 275, 0001, 366, 0024, 4267 (around twice that of the real L85) and finally 345fps.
When in deadly danger, when beset by doubt: run in little circles, wave your arms and shout
- Parody of the Litany of Command, popular with Commissar cadets.

#8
B00ts

B00ts

    AF-UK Newbie

  • Members
  • Pip
  • 16 posts

  • Guns: 2 star m4
    glock 18c
    Deagle
Sounds like the gun has bedded in and loosen up which is why its increased fps .

i've had guns change change fps from week to week without anything being done to it .

Instead of changing the spring try leaving the gun in the cocked postion( spring compressed) for a few days to a week ,this should bring the fps down abit .

As you can't see the spring without taking the gun apart look in the mag well at the hop up and your see the nozzle move backwards and forwards when the nozzle is in the open postion the spring should be compressed it may take a few shots to get it that way .
Never underestimate the power of stupid people in large groups

#9
Indieboi918

Indieboi918

    AF-UK Starter

  • Members
  • PipPip
  • 56 posts

  • Guns: Two Tone KWA KG36C
    TM M3 Benelli Super 90 (TT Blue)

  • Loadouts: Soldier '95 Camo
    CoverT 1/2 Finger Gloves
    British Army Assault Boots
Looked inside my magwell and fired a few shot but saw no movement at all, so I guess my gun is slightly different.

#10
kejot

kejot

    AF-UK Regular

  • Members
  • PipPipPip
  • 231 posts

  • Guns: CA M15CQB, TM 226, TM mk23 socom. All i need!!

  • Loadouts: loads but BFG's the best!!!!

  • Sites: UCAP's
also do you know what bb's were used each time?? a lower weight will give you a higher fps

#11
Indieboi918

Indieboi918

    AF-UK Starter

  • Members
  • PipPip
  • 56 posts

  • Guns: Two Tone KWA KG36C
    TM M3 Benelli Super 90 (TT Blue)

  • Loadouts: Soldier '95 Camo
    CoverT 1/2 Finger Gloves
    British Army Assault Boots
Yeah I used the same make of .20g BBs in each chrono

#12
JerseyRider

JerseyRider

    AF-UK Addict

  • Members
  • PipPipPipPipPip
  • 1290 posts

  • Guns: JG M4 S-system
    JG M4 CQB
    CYMA Glock 18C

  • Loadouts: British DPM's
    Warrior R.I.C.A.S Compact (OD)

Looked inside my magwell and fired a few shot but saw no movement at all, so I guess my gun is slightly different.


You wont be able to see anymoving comming from the magwell becuase the gearbox is behind the magwell and in frount of the stock

Even if you could see the gearbox trying to see the spring is a differnt problem all together

#13
B00ts

B00ts

    AF-UK Newbie

  • Members
  • Pip
  • 16 posts

  • Guns: 2 star m4
    glock 18c
    Deagle
The air nozzle travels backwards and forwards within the hop-up unit it what loads the next bb and is be visible while looking in from the magwell.

you may need a torch
Never underestimate the power of stupid people in large groups




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users