Is the spring the thing?

[Petro]

Hi guys,

Got an Ares G36C recently. Guy said it shot about 360 with 20's. Took it to a game and of course it didn't, was shooting around 295-300. Played the day and then took it home to figure out the issues. Noticed 2 things straight off, the spring was installed backwards (more compressed coils were not on the end of the spring guide), and secondly, very poor compression in the cylinder.

I Teflon taped the cylinder head and replaced the o-ring on the piston head and was getting very good compression after that. Flipped the spring the correct way and figured I was good to go. Went to a game yesterday and after fixing those 2 things, the gun chrono'd basically the same.

Can the spring wear out/get pooched from being installed backwards for too long as he had it and therefore need to be replaced or thing it's a leak somewhere else?

[Hectic]

Could be a leak in the hop up area. Nozzle to rubber, rubber to hop unit, rubber to barrel. Could just be a dead spring. Not sure that a reverse install would kill it faster but springs do die out over time. Leaving the spring Compressed definitely does kill springs.

[dmitril]

There is no backwards for a spring, newtons 3rd law. Also generally springs do not degrade from being stored compressed, rather repeated compression and more likely over compression will kill it. Also from my experience airsoft springs of lower quality tend to be over compressed by aegs hence loss of performance, but this will still take tens of thousands of rounds. Most likely your hop rubber is bad assuming you fixed compression. That was the case for my friends jg g36.

Edit: missed the fact you got it used in which case entirely possible for the spring to be worn out.

[Hectic]

Technically yes there is no backwards for the spring however it is coiled a certain way and intended to be installed a certain way. (It avoids binding of the spring and such) I'd argue however that leaving the spring Compressed for long periods of time will degrade performance. I lost about 60 fps on an m4 the last tooth broke on the piston the piston got jammed 90% to the rear and after about 16 months I finally fixed the thing but after the repair it dropped from 390ish to 330ish. Nothing else changed in the gun. New spring fixed it right up to 410ish.
It was a JG gun so I'd venture a guess that the spring wasn't all that high end to start and would also be open to the fact that a nice high end oil quenched spring should hold its strength longer compressed or not. But it's documented that compressing springs for extended periods does reduce their strength. Try leaving a magazine loaded full for 6 months then see how well it feeds bb's if at all

[Styrak]

but after the repair it dropped from 390ish to 390ish.

Hurr hurrr.

[Hectic]

Auto correct lol

[ThunderCactus]

Didnt someone do a comprehensive test like 9 years ago that proved non-linear spring lost 20-30fps when installed backwards?
Ive also had at least 3 guns that gained 20-30fps when i flipped the spring to the proper direction. I dont understand springs, i just understand the facts.

[EOD Steve]

Originally Posted by ThunderCactus

Didnt someone do a comprehensive test like 9 years ago that proved non-linear spring lost 20-30fps when installed backwards?
Ive also had at least 3 guns that gained 20-30fps when i flipped the spring to the proper direction. I dont understand springs, i just understand the facts.

Yup, that agrees with my findings as well. I also know of the thread you're referring to.

[dmitril]

Really? It disagrees with classical mechanics which tell use the tension in a spring is the exact same at any point on that spring. Also I have quick spring change gearbox and the fps for a spring has not chaned regardless of the direction I put the spring in if you are looking for evidence. And I am talking about non linear springs so popular in airsoft for no reason

[ThunderCactus]

Dont even ask me to explain lol
All i know is its been an issue for me and that was the fix. Could have been extreme coincidence that the issue was a mechbox misalignment? I dunno.
But i do recall someone actually doing a test and finding those results though... i agree it makes no sense to me either.
I know they have non linear acceleration, but i dont understand why that would change based on the direction of the spring. Id figure the difference of the spring having to accelerate its own weight wouldnt make a 30fps difference if that was the cause...

SO. Whos a mechanical engineer that deals exclusively with springs?

[Slodin]

maybe just swap out the spring? a spring is fairly cheap..10-15 bucks..
if it's still like that then probably somewhere is leaking..
process of elimination......It sounds like you bought it used, and who knows how many hands it has been in, so the spring might be worn out..(which would be easy)

[Danke]

A variable rate spring will react differently if you flip it.

The general idea is the light winding is at the start of of the cycle so it's easier to get it moving and he heavy rate is at the end when you have motion/momentum on your side.

So running one way or the other will change a variable.

In a suspension application running them wrong way can have even more unpredictable results if you have a linkage activating the works. That can have a rate that changes as the suspension arm moves through it's travel. If that leverage ratio was designed to take advantage of a light rate at the start and a heavy one at the end then flipping the spring is going to result in a really poor ride.