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Discussion Starter · #1 ·
Kinda curious about what spring snipers give the biggest joule difference between .48g at normal hop and .20g at the setting for .48g.

If you're wondering what the bigger question is, I'm wondering if long and narrow or fat and short cylinders of the same volume give different results.
 

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Both can probably create about the same. It depends on the piston weight and spring release. In saying this, I have found it easier to get more JC from long and narrow.
 

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I would assume long and narrow due to piston travel time. I think the striker with a Nemo kit (or the area copy) has roughly the same volume as an l96/aps2 but never seen anyone really joule creep that much on the striker so that's my reason for thinking this.

Might be worth seeing if anyone has posted performance with a Nemo striker to see if they joule creep much for a comparison to form a good hypothesis.
 

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As Ron said it has to do with piston travel. Slow movement at the start and fast piston movement at the end.

When the piston starts to move slowly this is when the light 0.2gm bb moves, then the piston starts to accelerate. The 0.2gm bb should exit the barrel when the piston has only part of the way through it's travel. This means that it was not up to it's full potential as the piston is still accelerating. The heavier bb is harder to push and so therefore takes longer to start to move. It should start to move once the piston has already gained energy and is part of the way through it's cycle. If timed correctly, to get the most efficient joule creep build, the heavy bb should exit the barrel when the cylinder hits the end of it's travel.
But this effect can be done with both a short piston and a long piston. It really depends on how the spring releases it's energy but it is easier to do in a long cylinder. Just put in the biggest spring possible and then add as much weight to the piston as possible (but there is a point where is can become too much but chances are, you will not get there).
If the weight is too heavy, the piston will have slow acceleration at the start of the movement and then as it travels though the cylinder, the piston will only gain a little more speed. In this case, you are best to remove some weight and the piston should be able to accelerate a lot better which will mean the heavy bb will also get more energy. But most people will have to add weight to get better effect with a big spring.

You can also create an inefficient joule creep build. This is done with an extra short barrel (so not the best cylinder to barrel to bb weight ratio) and this will give you less energy overall but a bigger difference in fps between the 0.2gm bb and the heavier bb. It is a lot easier to do in a bolt action and you will get better results than in an AEG. But by doing this on an AEG, I managed to joule creep about 300%. The 0.2gm came out at only 180fps (0.3 joules) and the heavier 0.45gm bb was shooting 0.9 joules. Now this same gun, when I tuned it to shoot 350fps with 0.2gm bb's (1.13 joules), was shooting 0.36gm at 1.7 joules. So not the 300% gain at the lower energy rate but still a massive advantage. (Note: I did not use this in game)
 

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Apparently, the PPS Mosin joule creeps a lot, though I am not sure why seeing as the cylinder is tiny.
Are you perhaps referring to the gas version? That would make a bit more sense. If it is the spring version you are referring to, that is pretty interesting.
 

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There are so many variables for joule creep, I don’t think it’s platform specific. Well I guess it can be since others are knowledgeable on model outputs but I am not. However here are a few things that have an impact:

Barrel length
Barrel bore
Piston length
Piston weight
Air brake?
Cylinder volume
Cylinder to barrel (to bb weight) ratio
Spring type

A lot of people notice how energy (joules) increase with heavier bbs. Is that joule creep? Yes, you are gaining energy. BUT I think actual joule creep is when you bring .20g fps and .40g-.48g fps outputs closer together. Take a typical rifle shoots that around 500fps with .20g bb. Drop a .48g in and set the hop. Depending on the barrel length the output is normally around 325-350 fps? Joule creep in my opinion is when the .48 is like 400+ fps, while the .20g output stays at 500 fps or less. I’ve been trying to get some good numbers but haven’t achieved anything spectacular yet. I’ve seen people say 500 with .20 and 500 with .48 which I think is impossible.
 

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There are so many variables for joule creep, I don’t think it’s platform specific. Well I guess it can be since others are knowledgeable on model outputs but I am not. However here are a few things that have an impact:

Barrel length
Barrel bore
Piston length
Piston weight
Air brake?
Cylinder volume
Cylinder to barrel (to bb weight) ratio
Spring type

A lot of people notice how energy (joules) increase with heavier bbs. Is that joule creep? Yes, you are gaining energy. BUT I think actual joule creep is when you bring .20g fps and .40g-.48g fps outputs closer together. Take a typical rifle shoots that around 500fps with .20g bb. Drop a .48g in and set the hop. Depending on the barrel length the output is normally around 325-350 fps? Joule creep in my opinion is when the .48 is like 400+ fps, while the .20g output stays at 500 fps or less. I’ve been trying to get some good numbers but haven’t achieved anything spectacular yet. I’ve seen people say 500 with .20 and 500 with .48 which I think is impossible.
that is not possible lmao
 

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I got 180fps with 0.2gm and 208fps with 0.45gm with that AEG I mentioned earlier. So having higher fps with the heavier bb's is possible. Though this was a stressful AEG build as the piston was really heavy, barrel was so short and the spring was so big. The barrel was actually only 40mm long. So it was flush with the end of the hopup chamber. It would be easier to produce bigger results with a bolty though this would come at the cost of higher fps because you need such a short barrel and most of us want the high fps.
 
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