how to lose 10fps?

[cannon_fodder]

I have a CYMA MP5 navy (CM041B).
When I bought it it crono'ed 360 fps straight out the box no problem as the sight limit is 372 max.

After a few thousand rounds and a clean and gease it now crono's at 375 and causes frowns from the marshalls

I need to lose 10-15 fps

As i dont know what rating the stock spring has I dont know which spring is one rating down.

Can anyone suggest a make and rating of a suitable spring.?

Is there any risk to cutting down / shortening the stock spring by a few coils?

[Gaffa]

Re: how to lose 10fps?

Wow, a site limit of 372... That's breaking the law, and it may be an idea to point that out. The absolute legal limit for an AEG capable of FA fire is 328, you're allowed up to 350 at some places because of Chrono Variations in readings.

If you want to lose that fps, just connect up a battery and magazine and fire off a few thousand rounds.

For a spring, go for an M90 or an M95 or even an M100.
So that's Systema or Prometheus really.

Element springs are okay, so you'd want the M95 or M105.

Or for guarder springs, go for the M90.

Edit - also it may be an idea to phone the retailer and tell them that your gun is firing at 360 when you bought it...

[omgitzjamiiee]

Re: how to lose 10fps?

Try dieting?

[Ominous Slayer]

Re: how to lose 10fps?

Wow, a site limit of 372... That's breaking the law, and it may be an idea to point that out.

It's 350fps (+6%)

[airsoft_ben_1989]

Re: how to lose 10fps?

you could use a velocity reduction silencer?

[Gaffa]

Re: how to lose 10fps?

Sorry Lee, this isn't the place to discuss it, but you're wrong...

1. All guns used in Airsoft games against another player must not exceed
328fps.
2. Sites may use a discretionary limit of +10% when chronographing guns.
3. It is advised that the discretionary upper limit is not publicised.
Exempt sites: Where a site has obtained specific and unambiguous written
confirmation from an insurer that the Public Liability cover provides for the use of
High powered, single action, sniper rifles then the Guideline limits will not apply.

Source : http://www.ukasgb.org.uk/ukasgb_guidelines_v3.pdf

That's the United Kingdom Airsoft Sites Governing Body.

[Caveira]

Re: how to lose 10fps?

Sorry Lee, this isn't the place to discuss it, but you're wrong...



Source : http://www.ukasgb.org.uk/ukasgb_guidelines_v3.pdf

That's the United Kingdom Airsoft Sites Governing Body.

But, that's not a LEGAL limit.

Having said that, home office guidelines now say 1J (roughly 328) where they used to say 1.35J. So, IMHO, you're not wrong, just quoting the wrong people.

[Gaffa]

Re: how to lose 10fps?

Ah well much of a muchness.

[Caveira]

Re: how to lose 10fps?

Ah well much of a muchness.

Very true

[The Keeper of Secrets]

Re: how to lose 10fps?

you could use a velocity reduction silencer?

Even the TM one only works for about 100 shots on full auto before the rubber gets ripped to shreds and it no longer works.

Best thing to do would be to leave it overnight with the spring compresed (i.e with the gun halfway through a shot). Or take it apart and downgrade.

[richardy]

Re: how to lose 10fps?

Even the TM one only works for about 100 shots on full auto before the rubber gets ripped to shreds and it no longer works.

Best thing to do would be to leave it overnight with the spring compresed (i.e with the gun halfway through a shot). Or take it apart and downgrade.

do this .........

[cannon_fodder]

Re: how to lose 10fps?

I'll try a 105 spring as I'm guessing that it has a M110 fitted but the type might depend on whats instock..... ZeroOne have got loads of choice if you want 400+fps not so much choice for weaker springs.

I gutted about having to open the gearbox.... This has been the one clone that give clones a good name (so far) range and accuracy have been perfect so far. Solid build and no obvious defects....
I know if I open it up I will probably find some horror story inside that will ruin the honeymoon

[The Keeper of Secrets]

Re: how to lose 10fps?

If you're terrified of opening up the gearbox, then leave the spring half compressed overnight as I suggested previously.

[gundown]

Re: how to lose 10fps?

just do what was said before and leave the spring compress for day and that should do it if it's only 10 fps. or shoot a couple of mags thought it. I had an AA r85 and it was shooting 400 fps put a couple of mag thought it got it shooting 365 but by then end of the day it was down to 320 fps.

[cannon_fodder]

Re: how to lose 10fps?

I do all the repairs for my squad so Ive changed a few springs and rebuilt and shimed a few destroyed gear boxes.
I just dont have the time for a rebuild this week.

I'll take your advise and compress the spring for a day or 2.. so I'll try a few shots on auto and see if I can get the spring to stay compressed