Joule Creep

[proffrink]

This topic has been split off from another to allow the original topic to stay on track.

Joule creep also means you might be further from that 2.3J limit than you think when you switch ammo. Test with the weight you're going to use as - at 500ft/s on a .20g - you'll certainly be getting some when moving to a sniping weight.

I would just be cronographing with your intended weight right now and calculating the Joules. Most chronographs will do this for you if you put the BB weight in. 2.32J is the limit for 500ft/s with a .20g BB, so that's about 365ft/s with your .40g BBs.

 

[Rogerborg]

I would just be cronographing with your intended weight right now and calculating the Joules

I agree in principle.  In practice, as long as sites keep testing guns with 0.2g, I'd tune for 0.2g and let them worry about Joule creep.

I don't like it, but why disadvantage yourself against everyone else who's tuning for 0.2?

 

[proffrink]

Well that's your prerogative, but you'd be consciously shooting a hot gun.

 

[Rogerborg]

you'd be consciously shooting a hot gun

How would I know that, when I always chrono with 0.2g?  Why would I chrono with anything else?

If I do Joule creep (again: how would I know?) I'll be no hotter than every other 500fps x 0.2g sniper user on site.

Sites should know this - it's their day (or at least weekend) job.  I wish sites would chrono with heavier BBs, but I can't force them do so.  Nor can I level the playing field by digging a foxhole for myself.

 

[proffrink]

Because there's no case in airsoft where using a higher weight BB won't result in a higher muzzle energy with all other variables equal (power source, barrel length etc.). The change might be slight on an AEG which is under-volumising a barrel, or might be greater on a GBBR, but it will always be there.

You will always be shooting hotter that the cronograph says if you switch up ammo. You can have the argument that your site should check it (and they should) and I'm sure you could convince many - if not all - people that this is fine (it's a negligible increase) but you are shooting a hotter gun that you intended and - if you're hitting that 500ft/s limit on a .2g BB at the crono, my contention would be that - knowing what you now know - that you're consciously shooting a hot gun.

The two aren't mutually exclusive, and I've given up on hoping that a particular site might understand Joule creep properly, but as an HPA user I need to rule it out. There - in particular - many GBB and HPA users who don't realise this (and the results tend to be more noticeable with those higher volume gas guns like HPA, green gas and most sniper rifles too) so I do take extra care. Where you might sit on that spectrum and where you draw the line is your choice but I don't have the time to evaluate what your gun shoots and how fast; I'd only ask that you don't dismiss it immediately because it's the sites responsibility.

 

[Duff]

Maybe they should have a guideline of what weights to use on certain weapons ie; aeg, dmr or sniper.... and confirm what weights you'll be using in play. Or just chrono once on .2 then on the actual bb weight that it'll be firing....

 

[Rogerborg]

if you're hitting that 500ft/s limit on a .2g BB at the crono, my contention would be that - knowing what you now know - that you're consciously shooting a hot gun

If I hand my gun to someone who doesn't know about Joule creep, will it shoot heavier BBs with less energy?  If not, then I'm not sure why the shooter's awareness of it would matter to the target.

If it's shooting over 2.5J then it's not an airsoft gun.  My springer may be capable of that, for some mass of BBs, but how would I know, since I only ever chrono with 0.2g, as required by the sites at which I play?

For anything less, what constitutes a "hot gun" is entirely up to the site to define.  If the only definition that they provide is "500fps with 0.2g" (as most do, sadly), and mine comes in under 500fps with 0.2g (and it does), then I am not and can not be "consciously shooting a hot gun" if I switch to heavier BBs, since there is no other reasonable metric that I can use.  If they specified an energy limit with the mass of BBs that I'm using then I'd stick to that.  But they don't, so I don't, and I'd be astonished to find that any other player was doing so.  Why would we?

I don't agree with that situation.  But my conscience remains entirely clear.  It's up to sites to change their definition and chrono procedures, and I'll be making that point to any sites that I use my sniper at in the future.

 

[proffrink]

I'm unconvinced but I can see we both have our way of doing things.

Maybe they should have a guideline of what weights to use on certain weapons ie; aeg, dmr or sniper.... and confirm what weights you'll be using in play. Or just chrono once on .2 then on the actual bb weight that it'll be firing....

This is the solution, but unfortunately some struggle to get their head around what muzzle energy it (and this includes site owners). I have also met a couple of marshals who will do the calculation quickly in their head if you're using a certain common weight (but this has only been for .25s and .20s to speed up cronoing).

 

[Duff]

I'm unconvinced but I can see we both have our way of doing things.

This is the solution, but unfortunately some struggle to get their head around what muzzle energy it (and this includes site owners). I have also met a couple of marshals who will do the calculation quickly in their head if you're using a certain common weight (but this has only been for .25s and .20s to speed up cronoing).

If you don't understand joule creep and weights then you shouldn't be in charge of chrono. H&S in this sport is something that gets harked on about yet most have no idea. 

Including myself, I have zero knowledge of joule creep versus bb weight ratios buy I would happily spend half a day in a classroom learning.

 

[Tackle]

I'm like duff, know shite about joule creep, in fact didn't know of its existence until recently & I've been playing for 17-18 years, just goes to show your never too old to learn something new.

Regards h&s, too many variances between sites, one won't even chrono, another will, another will but with the addition various megs loaded with identical bb's for consistency, the list goes on & on, & that's before we even factor in the cheating motherfuckers who'll do their best to beat the system, additional hot guns/hpa/etc etc........ needs to be a uniform solution that all sites can & will adhere to, without too much confusion & uncertainty.

 

[proffrink]

additional hot guns/hpa/etc etc........ needs to be a uniform solution that all sites can & will adhere to, without too much confusion & uncertainty.

I agree that there's no easy solution, but the uniform solution is to measure muzzle energy not 'fps' and to make you shoot the BB you're going to use on the day. There are ways to cheat this though (I'd perhaps spot check every 10th player or something and weigh the BB they're using, but that's a lot of fuss).

Also remember that when you refer to HPA being a cheaters choice that we've had NPAS for GBBRs since the early 2000s and those are just as easy to cheat with. I know you're just giving an example, but tournament locks exist for HPA and if a site wants to enforce them they can really easily (in fact almost all regulators now have them built in). Nothing can account for lazy marshalling and paranoid players unfortunately.

 

[Tackle]

But we go on a lot about cheating players, something I don't think will ever be eradicated, but how do we ensure that those running the sites give a rats ass, yep theres a lot out there who are fairly stringent about gameday chronoing, BUT ONLY FOR FPS, there's just as many using cheapest chrono they could find, manned by barely literate staff (I know a few sites like this), surely the only peeps who could pressure organisers in to doing adequate muzzle energy tests would be the insurers ?

 

[LightningCh]

I can see exactly what both sides are saying in this argument. With my jump to HPA I guess i'm lucky in the sense that I won't ever be running .4s in my evo ??

But at the same time, i agree with the idea that my conscience is clear if it chronoes safely with .2s because that's what the site wants.

The simplest way I can see of doing it is to load the players mag with a couple of the heaviest bbs on the market, and then chrono the joule reading from there. (You'd only need 3 numbers because of the types of gun, AEG, DMR, and Sniper)

 

[Elmer]

Thankfully my local site crono on the weight you are actually using but that does rely on the players honesty there is nothing to stop cheats saying they are using 0.2 or 0.25g when in fact they are shooting and chronoing with far higher weights.

 

[sonofsammo]

Shot with the same gun on consecutive shots, using mags on the same gas, from the same can...
One is on .2's, the other is on .4's.
By the site limit rules of where I was playing yesterday, and going by the 350fps limit, I could have used it the same as an AEG, even though it should be classed as a DMR.
So, 1.66J and no MED.....
Going by Joule conversion, that would be the same as a .2 @ 420 fps - at whatever range I fancy AND on full auto (I'd have been able to swap the fire selector back to one that gives full auto)? By anyone's standards, surely that's just bonkers??
And potentially dangerous?

View attachment 36190

View attachment 36189

 

[sonofsammo]

500 fps on .2 is 2.32J
2.32J on .4 is 352 fps.

Why on .2? Speed, laziness.... No idea.
Some sites chrono on what you're using - but don't seem to know how the tables work for conversion.
Some sites chrono on what you're using and do understand and apply appropriately.
Some sites chrono on .2 and really just don't give a fuck.
And then there are places in between all of those.....

 

[proffrink]

It is super simple though if you have the above chart I posted.

As @sonofsammo says: You just convert what the site limit is into Joules (which is what the government uses anyway to measure how 'safe' a gun is). Remember a train going at 15mph has a lot more energy than a car going at 100mph.

So 500ft/s on a .20g BB is 2.32J. Therefore 2.32J is now your site limit for sniping. What ft/s that is on your particular ammo is in the chart below.

Joule creep only kicks in when someone cronos with a lower weight and then uses a heavier BB for their games. This is down to - as a simplification - a slower (i.e. heavier) BB in the barrel attaining more energy from the same amount of air/green gas during its journey down the barrel than if you were using a .20g BB that will leave the barrel sooner and be on its way with marginally less energy. This is more pronounced the bigger the difference between the two weights, so it's a particular problem for DMRs, bolt actions and - unfortunately - HPA users who will typically splash out on .32g BBs.

Shot with the same gun on consecutive shots, using mags on the same gas, from the same can...
One is on .2's, the other is on .4's.
By the site limit rules of where I was playing yesterday, and going by the 350fps limit, I could have used it the same as an AEG, even though it should be classed as a DMR.
So, 1.66J and no MED.....
Going by Joule conversion, that would be the same as a .2 @ 420 fps - at whatever range I fancy AND on full auto (I'd have been able to swap the fire selector back to one that gives full auto)? By anyone's standards, surely that's just bonkers??
And potentially dangerous?

View attachment 36190

View attachment 36189

This is unfortunately why I take the option of doing this myself. The increases are significant and sites don't care - doesn't mean I want to shoot hot guns though. Especially what with being careful with HPA. GBBRs are also very bad for Joule creep.

 

[Sacarathe]

See the chart in the original post. It might help if you read the page it comes from. http://www.airsoftmaster.com/fps-chart-for-airsoft-guns/

The thing to remember is that what you're trying to find is the power of the gun, and one of the factors in determining this (see the formula) is the projectile's mass. If you change the mass you invalidate the test.

Take a Cricket ball and a Tennis ball. Throw the Tennis ball against a solid surface (such as a window), now repeat with the Cricket ball. If this is too complicated then you broke a window, if it's not too complicated you realise what's happening. ?

Same basic principal as in airsoft. Would you presume that the results from the tennis ball could be applied to the cricket ball without performing the test?

 

[Immortal]

Joule creep isn't really necessary to understand mathematically but it does make perfect sense as far as a chrono result goes. The charts are accurate enough to know if your shooting hot or not. Plenty of good simple explanations given above so I won't bother to repeat.

It should be the players responsibility to know their joule rating with their intended ammo weight IMHO. Sites should also understand this if they respect their customers wellbeing and enforce it.

It's a game with a little pain but not intended to maim. (lol... sounds like a shitty song line...).

It's a little dissapointing when people don't care about what they're potentially inflicting on others.

 

[Rogerborg]

It should be the players responsibility to know their joule rating with their intended ammo weight IMHO

It should be sites' responsibility to specify limits in Joules, and to chrono with heavy BBs.

I opine this because how can players be expected to know that it's even an issue?  Sites typically only talk in terms of fps x 0.2g. Euro retailers may mention J but UK sites like patrolbase only list fps x 0.2g.  A typical Facebook group isn't going to vomit that pearl of wisdom into the "noice m8" word salad.

So really, how are players supposed to know?  And why would they seek out that information, if their site says and tests "500fps with 0.2g"?

We could wish that it were otherwise, but that's about as effective as wishing for Kate Upton duct taped to your bed.

The small minority of players who are inquisitive enough to seek out forums rather than Facebook, stumble on threads like this, and then actually penalise themselves by chronoing well "under" with 0.2g can pew with a clear conscience.  But the majority of sniper / DMR / HPA BBs flying around are still going to be "hot" and the problem isn't solved.

Sites need to lead on this.  Perhaps their insurers need to make them do so.