Okay it seems like people don’t get the reason for HPA having less joule creep then spring powered systems.
Okay to start off with.
what creates Joule creep.
I already have some notes on this in this post here. “Link”
But here is the short version.
Okay we have 3 things we have to worry about.
1. barrel ratio.
2. Spring strength.
3. bb weight.
And the thing that happens is as follows.
The spring pushes and compresses the air behind the bb and pushes the bb out the barrel.
And let’s say we use a light weight bb and the air reaches let’s say a compression of “2” (this is an arbitrary number that has no significant value. It is just to make an example.)
So in this state the piston has 2 times the resistance compared to not having a bb in the barrel.
And this will cause the piston to travel slower.
And because of this we have a potential of joule creep.
And let’s say you use the exact same system but with a heavier bb.
Now with this bb we get a compression of “4”.
Now the piston has 4 times the resistance and will use even more time. But as we already know even a slower heavier object can have more force,
than a lighter faster object.
And that’s not all.
As the lighter bb only needs x amount of force or energy to be moved let’s say 1.5 while the heavier bb needs let’s say 3 or 3.5.
The heavier bb will have this amount of energy stored behind it for a longer time. And will therefore have this amount of energy behind for a longer period of time in a spring powered rifle.
And the more time it has means there is more potential energy at play.
Then in a HPA system.
Look at it like this.
When the piston is released it moves x mm before it has enough force to push the bb past the hop-up.
In the same way as the piston only moves x mm if you have 100% airseal and you block the nozzle.
And after that the pressure will stay the same if not get higher, until either the bb is out of the barrel or the piston reaches the end of the cylinder.
(and that is where the barrel ratio comes into play)
But in a hpa system it is not linear or increasing like in the spring powered systems. Therefore defeating a major part of joule creep.
As it releases at a set pressure of lets say 45 psi and it will get lower the further down the barrel the bb is.
Now the difference won’t be a lot but the devil is in the details. Much in the same way as with the time it takes for the piston to reach the end of the cylinder.
Now of course having a huge volume will negate the pressure fall, but it will not remove it.
And the only way you could fix it would be to have a system that increases the pressure over a split second time window.
But I don’t imagine that coming out on the marked any time soon, or for that matter ever coming out.
Now yes I realise the solenoid on AEG conversion kits like the polarstart and wolverine, does this to some extent. But this is fixed.
And does not change in the same way as the piston in a spring system, depending on bb weight. so this won’t really count.
And for this reason you will not have the same potential for joule creep as you would with a spring powered system.
And as you might have guessed this will make the Joule creep lower or literally close to non existing.
As it is with my VSR-10 G-Spec (at the moment of writing .02 joule. with a barrel ratio of 3.6:1)