Airsoft Sniper Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
80 Posts
Discussion Starter · #1 ·
Hey guys.

Wrote this article today: http://2shots1kill.com/joule-creep-testing/
After completing testing with different ammo weights.

When I stopped playing airsoft in 2010 joule creep wasn't really a discussed thing, and pretty much an unspoken / unknown thing, at least at the sites and players I played with and at in the UK.

Only really found out about it after one of my local sites have a max ammo weight to prevent joule creep.

So I researched it further and did some testing.

I actually ended up eliminating joule creep from my rifle by cutting the spring down it appears. I'm going to retest this theory shortly when i get a new spring to try with.

Be keen for your feedback and thoughts. (if you could use the comments on the site it would be great to get a discussion going for non-members of this forum to see).
 

·
Registered
Joined
·
5,310 Posts

·
Registered
Joined
·
80 Posts
Discussion Starter · #3 ·
Hey 1tonne,

Thanks, I think I've actually read that post before.

I'm actually happy I've eliminated the joule creep. As one of the reasons one of my local sites doesn't allow heavier weight ammo (.3 for sniper rifle and .25 for other guns) is due to them believing heavier ammo causes joule creep. But this isn't technically correct.

Do you believe that having a less compressed spring would cause less to no joule creep?
The simple job of buying an over powered spring and trimming it causes the joule creep to be gone?

I used to always trim springs down as it made the bolt pull easier and allowed me to get a more precise fps
 

·
Registered
Joined
·
4,148 Posts
Joule creep is the result of piston travel speed, barrel length and the cylinder:barrel ratio involved. A cut down spring actually makes the piston travels faster at first and then accellerate slower compared to a normal spring, because the force is less uniform. Joule creep is the result of the .2 leaving the barrel before full compression of the cylinder, which is due to slow initial movement of the piston, rather than fast. Following this theory (as explained by 1tonne), I would say that a cut-down spring therefore indeed experiences less joule creep because of the faster piston travel.

But, it depends on a lot of variables :hehe:
 

·
Registered
Joined
·
80 Posts
Discussion Starter · #5 ·
That makes sense!

Also fits my findings.

Just wish I had heavier ammo when I originally installed my upgrades.
Got to wait for a new spring now.
 

·
Registered
Joined
·
5,310 Posts
It does depend on a lot of variables.
I have found that the stronger the spring, normally the more increase in JC. So if you do cut one, this would make the spring less strong, decreasing the JC.
To get a perfectly tuned rifle while using heavy weight bb's and no JC, you need the correct barrel length for the heavy bb and a piston that is as light as possible. So you could try a plastic piston and drill holes in it. Also, if you have a bad air seal you can lessen JC. A bigger bore in your barrel will also decrease the JC effect.
 

·
Registered
Joined
·
80 Posts
Discussion Starter · #7 ·
I've just received this morning a new PSS10 130SP Spring.
This spring also gives me 481-486fps with .2 (2.17j ish)

However, unlike the cut-down spring where using heavier ammo gives the same joule output, using .36 this uncut spring gives me 2.4j (510fps with .2 equivalent).

Hopefully I'll get chance to do a bit more indepth testing soon comparing the 2
 

·
Registered
Joined
·
4,148 Posts
That makes sense, yeah. More constant force from the spring so less initial acceleration so more joule creep :tup:

Also... What's the weight of your piston? Lighter pistons will also yield less joule creep (as explained by 1tonne)
 

·
Registered
Joined
·
4,148 Posts
That's a pretty light piston then... If you want even less joule creep you could switch to a plastic piston but honestly the AA one is probably just fine :tup:

Another way to prevent joule creep from happening is to set the hopup to be tuned right for whatever heavyweight bb you're using and then after that chrono it with .2 and making sure that that fps with .2's doesn't go over your limit, as it will be closer to the muzzle energy with the heavyweights once the hopup is set :tup:

But for some reason some sites (such as all sites in the Netherlands) require you to chrono with hopup off :doh: :lmao:
 

·
Registered
Joined
·
80 Posts
Discussion Starter · #11 ·
That would be frustrating having to reset your hop after every chrono test!

I just think, chrono gun with ammo and hop set that they are going to use and then make sure the joules is the same or under the site limit. Much easier!
 
1 - 12 of 12 Posts
Top