Spring differences

[Dimitri]

From what I can gather the spring in say my Ver 2 G3 gearbox and the spring in the Ver 3 SIG-552 gearbox are the same?

I can swap out the lower one that came with my G3 and put it into the SIG's gearbox to make drop it to UA's fps limits?

Dimitri

[pestobanana]

AEG springs are all the same. Make sure you chrono your gun before going to UA though, different guns will get different velocities with the same spring.

[Dimitri]

Very true about fps differences, but like when I switched the spring on the G3 I don't have a chrony so will have to let UA test it afterwards.

Dimitri

[ThunderCactus]

Things like piston head bearings, spring guides, compression leaks, hop rubbers, barrel lengths and barrel bores can affect the fps of a given rifle.
If you know for a fact a given spring is say 350fps under ideal circumstance (like the ratings on the ASC spring chart), then you're golden because the fps can only go down from there, it's rare to go 5-10fps over.
But if your spring is 350fps in a given gun, and you don't actually know what the spring is rated to, then that spring could push anywhere from 300 to 450fps in another gun.
But if it's a stock spring, then you've got a very reliable 5-15fps window to work with. Like if it's a classic army stock spring, they're all within 310-330fps

[Dimitri]

Originally Posted by ThunderCactus

But if it's a stock spring, then you've got a very reliable 5-15fps window to work with. Like if it's a classic army stock spring, they're all within 310-330fps

It is indeed the stock spring that came with the CA G3 in a bag separate from the gun due to the upgraded spring installed for Customs purposes.

However, in the G3 it's shooting at 350fps based on UA's chrony measurements when I go to play.

But I figure with the much shorter inner barrel in the SIG, it should lower velocity not increase it?

Dimitri

[Rusty Lugnuts]

Be carefull to put the tighter wound end of the spring (if it has one) against the guide. IMO that affects fps as well

[Dimitri]

Interesting, thanks for the tip!

Dimitri

[ThunderCactus]

Based solely on having a shorter barrel, assuming it's of the same bore, the mechbox is the same, and the cylinder volume is correct for the barrel, then it should either stay the same or decrease only slightly.
Piston head bearing and spring guide bearings alone can gain 10-20fps.

[Dimitri]

I realized my SIG-552 needs a lipo battery and the mini I have kicking around wont fit.

I think I'll just pick up a M100 spring when I get the battery and leave my G3 UA legal as a back up, until I eventually turn it into a semi-auto only DMR that is.

Dimitri

[ThunderCactus]

Ah, I always love asking about this
By your wording I'm assuming you're going to raise the fps above what's normally allowed into a semi-only category
What's your reasoning for building a semi-locked, higher FPS, DMR platform? Range and accuracy? And specifically, what kind of ammo will you be running at what muzzle energy?

[Dimitri]

Mainly to increase it's max effective range.

Velocity is secondary to accuracy. It depends the route I take.

Depends what route I take with it,

Either up the velocity while using heavier BBs (.30-.38) combined with a Promethus tight bore barrel.

Or use .25-.30 BBs with a twist barrel then velocity is limited to 330fps due to the twist barrels velocity limitations.

Combined with a better sealing cylinder/piston/nozzle, better spring guide and having R-hop installed. To help make it a little more consistent.

If I go with a traditional tightbore I'll experiment on spring strength to see where I get the best effective range, always).somewhere between 400-450fps (chrono with .20g as always).

Dimitri

[Dimitri]

I picked up a Element M95 from Toronto Airsoft on the way home today, will install it in the Sig-552 tonight and hope for the best.

Dimitri

[ThunderCactus]

FYI the twist barrel is not a magical item lol
It doesn't improve your range any more than a widebore would
How it functions is it just provides channels for more air to help center the BB, it does NOT induce any sort of rifle spin to the BB.
The amount of axial spin generated by the hop up acts like a gyro on the BB, making it extremely difficult to induce spin in a different direction.
And if rifle spin WERE induced on the BB, you would see it veer off to the side all the time near the end of it's flight path.

You're actually better off using a widebore or tightbore, I personally recommend the 6.08 or 6.05, and using heavier BBs.
The actual bore and length of the barrel is inconsequential. All barrel bores (within a range, of course) will produce the same accuracy, but the tighter bores will lose accuracy faster due to fouling. It's been my experience with my VSR-10 that after just 120 rounds the 6.03 barrel lost a noticeable amount of consistency.

Now you're very close in saying that velocity is secondary to accuracy. What actually determines the maximum range and accuracy you can have is the weight of your ammo.
Heavier rounds have a higher maximum range and accuracy than lighter rounds.
But of course you need the muzzle energy to get them out there.
So all BB's optimally end up being at a relative speed of 320-350fps.
The more you increase your muzzle energy, the heavier the ammo you should be using, but the relative speed of the BB typically stays at 320-350fps.

Issues occur when you're at high fps with too light a round. Either the round loses it's momentum too quickly (lighter rounds lose momentum faster than heavy rounds) and destabilizes, or you're actually sending it out so far that it's hop up spin destabilizes causing it to veer off in a random direction before gravity is able to pull it to the ground.

With my VSR-10 I found that at 430fps, .30g BBs worked just perfectly. But bumping it up to 470fps, the .30s would flay out at the end of their flight path.
So generally just use .30s up to 440fps, and .36s beyond that.

So pick an fps, and just get 3 different weights of ammo and compare those to get your best performance.
You just want to see which BB's will go the furthest without flaying before they hit the ground. Ammo that is TOO heavy will reduce your range.

[Dimitri]

Interesting, thanks for the insight.

By the way, the Version 3 gearbox involved less swearing then the Version 2 of my G3 to swap the spring. I am either learning, or the Version 3 gearbox is simpler.

Dimitri

[ThunderCactus]

I know lots of people say that, personally I hate V3s so damn much. But then 90% of the mechboxes I work on are V2 lol