Downgrading by cutting spring.

General Grobel

Right, I need to downgrade an AEG and dont have time to get a 1j spring for Sunday so I was wondering how much of the spring do I need to cut to make it shoot at 1j aprox. The spring is from a very old cyma ak47s that was laying around.
Cheers.

Leftyflip

What is it firing at now?

General Grobel

I'm a poor bastard so I don't have a chrono but using a can it pierces both sides of and goes through the middle bottom of the can.

.22 Lover

That means nothing i can pentrate a can with my finger your gun might not be illegal but id take it to a airsoft shop they mostley do it for free and its still better then a garde doing it for you.

General Grobel

I was using the poor mans chrono to gauge a general idea of FPS. I don't know any airsoft shops that will do it for free plus im a far away so Ill have to do it myself using alternative means. What happened was that my LEGAL spring decided to destroy itself so I replaced it with the only spring I had laying around which I though was an m90 or something like that. SO I just need an alternative, temporary way to reduce power.

Sorry about that wall o' text but there ya go, any advice would be much appreciated.

Leftyflip

General Grobel wrote: »

I was using the poor mans chrono to gauge a general idea of FPS. I don't know any airsoft shops that will do it for free plus im a far away so Ill have to do it myself using alternative means. What happened was that my LEGAL spring decided to destroy itself so I replaced it with the only spring I had laying around which I though was an m90 or something like that. SO I just need an alternative, temporary way to reduce power.

Sorry about that wall o' text but there ya go, any advice would be much appreciated.

Don't all airsoft shops chrono for free?

General Grobel

Jesus I'm tired, I thought he meant downgrade for free. Chrono isn't to much of a problem, I can usually judge the FPS ok.

.22 Lover

I dont know ive never tried im just assuming as i dont think they can charge to shoot your gun into a what is essentchually a ray of light

hairyman

If it can do the bottom of a coke can then i would be inclined to think that it is over the limit,,

What length inner barrel are you running,,,if you have a longer inner barrel lying around then you could use this(concealed in a mock silencer) as a quick fix to lower the FPS due to the lack of bore up and have it game legal by Sunday.

Dread-Lock

Sorry but I have to say that "poor mans chrono" is a load of BS, it means nothing.


If your cutting the spring you really need a chrono to test it. If you do cut the spring, remember a little goes a long way.
My sniper was shooting a little low (around 260fps) so instead of buying a new spring I put a small bit of tubing on the spring guide to raise the fps. I put 16mm+/- of tubing in it and it raised the fps by over 100. (This was way too much so of course I opened it back up and cut the thing in half).

Masada

Yup, defo get it chrono'd before ya start chopping. it might be legal. cans very from place to place, and this method came from america. you'll notice they never have the same cans or bottles as we do when your on holiday. that said, even if i had an american can i wouldnt have any faith in the method.

blacon9

I disagree, I think if it goes through both sides of the can every time then it's defo over.

My gun is JUST under and it only goes through one side. My friends gun is over and it goes through both sides.

If it shoots through the bottom of a can, it MUST be over the limit.

You'll need a chrono to test the new fps after cutting it though.

Witcher

The can test does not work:rolleyes: there's differences in thickness' between all the different brands so how can there be a standard for a can test when every can is different? The thickness of the can, weight of bb, distance, angle are all variables which will throw the result off.

It doesn't work, a chrono is the only way to know for sure if its over or under.

Inari

As has been said, can test is bull ****. Too many variables. Best thing to do is Chrono it.

Firekitten

.22 Lover wrote: »

That means nothing i can pentrate a can with my finger your gun might not be illegal but id take it to a airsoft shop they mostley do it for free and its still better then a garde doing it for you.

Actually, yes, your finger can penetrate a can, but the kinetic force your finger applies to break the material will be the same as the bb.... it just wont get there as fast.

hairyman wrote: »

If it can do the bottom of a coke can then i would be inclined to think that it is over the limit,,

What length inner barrel are you running,,,if you have a longer inner barrel lying around then you could use this(concealed in a mock silencer) as a quick fix to lower the FPS due to the lack of bore up and have it game legal by Sunday.

A longer inner barrel will NOT drop his fps, not unless its significantly longr, or shorter, will the cylinder type make any difference. If its over 350, it will be non vented, and as such, will have 0 difference, if its under 350, with vented, and you extend the barrel, it will drop the fps, but it will also shoot terribly due to suckback in operation on the bb.

Spetzcong

To take a somewhat silly thread and point it in a more sensible direction.

When cutting springs, is there a guideline on how many FPS each coil of the spring will reduce the FPS by or does it all depend entirely on the FPS of the spring in the first place?

Also I assume that you cut the non thickly coiled end of the spring, correct? (well I hope so, coz that's what I've done on every spring I've cut in the past)

Dread-Lock

I think it would depend on the spring, but I was told awhile back (can't remember who) that each coil is roughly 10fps. No idea if thats even remotely accurate.

Puding

What length inner barrel are you running,,,if you have a longer inner barrel lying around then you could use this(concealed in a mock silencer) as a quick fix to lower the FPS due to the lack of bore up and have it game legal by Sunday.

as fire kitten said it will loweer fps but only when your cylinder volume is greater than the volume of the barrel, when this happens the bb will slow donw in the barrel due to friction, somthing which will decrease preformance in a big way

i would not trust the can method as far as i can throw it, yes its great for tell if an aeg is 300 ish or 400fps ish but can it tell the differance between 320 and 340 ? no it can not, unfortuntlay we do not have any +/- in yout law so a chrono is the only way to go

10 - 15 fps per coil is about right for a 400fps spring from what i;ve read, but i would not trust it,

Firekitten

Let me tell everyone a story here....

I bought an AK74 while i was back in Ireland, and naming no stores, and naming no people, the technician in question that had downgraded that weapon to the legal limit, whether that was in country or abroad, had decided to cut the spring....

It's an aside that they didn't have a clue how to put an ak selector back on.... ah well, i can forgive that. but when I crono my lovely ak74n at a game, it reads 230fps... out the box.... NEW....

Now this is a tad hinky... so off I tootle home with my toy, and take it down... lo, what do I find?

Said muppet had clipped the spring... a stock kalash spring... roughly 420.

Now getting this down to 328 would involve throwing out roughly half the spring.

Which he did.

thus, my rifle sounded like an outdated sound effect for the muppet show each time it fired.

Clipping springs is not a be all downgrade method. It will not work in any case. It is suitable, for when one has a gun shooting say... 335, and you want to get it JUST down, without chaging structural length much. (it is important).

Tips: Make sure if you cut, its from the NON tightly coiled end, and also flatten off the coil one cuts.

For this case.. I suggest spending a whopping 10€ and buying a 1 j spring, you have no crono, and your coke can method will surely keep you refreshed, but not with an accurate fps reading.

Masada

Halving a spring, (especially a standard Kalash one since they are a lot shorter than typical 1J springs) would mean it was no longer big enough to fill the stroke of the gearbox and wouldn't return the piston to the front properly since its slack and not under any compression when the piston is forward , resulting in the sector gear coming around for a visit and ruining your piston.
Id say he low FPS would be the last of your worries.

General Grobel

So in other words, If I'm going to get it done I should get it done properly? Well that's what I'll do then, sorry about this silly thread and thanks to those who gave constructive advice.
Cheers.