JOULE CREEP - WHAT IS IT AND WHY DOES IT HAPPEN???

This video explains what joule creep is and touches on one of many reasons why it occurs. There are many other contributing factors to the phenomenon outside of what is explored in this video however, this video goes through the main contributing factor and also explores ways in which airsofters can avoid it and play within the legal limits to secure our sport as a safe one in the future
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[@LöwenTarn]

„Right?“ 😉

[@jackal187]

Well explained and you kept it simple for everyone to finally understand. Since I started I have kept my guns as close as possible to the 1 joule using the weight bb I intend to use.

[@FOXGREEN]

Thanks man 👍😁that the only safe way to do it. You cant go wrong then 👍👍

[@ALEX-xd7ko]

Heavy bb = harder to move , so more of the volume is used before the bb exites the barrel .

[@FOXGREEN]

Yes that's correct also. This as I say is just one of many reasons why it occurs .

[@anomalyp8584]

Interesting. I always viewed this from a 'efficiency' kind of deal. But now I know where the difference in efficiency comes from. I'm thinking Bernouili principle. I was thinking more along the lines of: a 0.2g bb will speed up fast when pushed forwards, so fast that it is still accelerating when at the end of the barrel...so the rest of the energy leaves the muzzle as turbulent air + sound. A heavier bb will travel the same barrel distance in more time, so it has more time to 'extract' the energy from the air that pushes it forwards. So ideally, the BB stops accelerating exactly when it leaves the barrel and the air behind it is at a standstill. Basically the sequence with 0.2; piston movement divided over BB and air combined. With heavier BB like 0.40: piston movement --> air movement --> bb movement.

[@andrewsupernova]

Great vid, very informative and simple when explained so well. Thanks and keep up the great work.

[@robertyoder9704]

I will say this for now. The video may not have any gameplay but at the same time it wouldn't be necessary for this type of video, to simply put it, the only BBs I have are as follows: 0.12g, 0.20g, and 0.25g. I have a basic sniper rifle and 2 types of pistols 1 electric 1 strictly spring, "bleh". Needless to say this video is informative and allows for the understanding of joule creep. Now it's only my opinion as my way of learning is slightly unique, and no I will not explain it, as is the example he gave does make alot of sense to me. Fox, I have to admit I was more then a little curious as to which would hurt/which would I feel more between the different grams I possess, and I was planning on having a relative I trust shoot a few rounds at me from the same distance so the results wouldn't very much, but the example you have given has me more curious to find out and feel it for my self, granted I have an idea of what to expect now. At some point in another one of your videos if you don't mind, I would like to post my findings on the comments after it's done of course. Thanks again for the video loved it, hope to see more in the future. Keep doing what you do and as always stay frosty.

[@FOXGREEN]

Yes please post away I would love to get some of your finding in my comments we all need to help each other as airsofter to understand every aspect of the game especially when it has a legal standing 👍

[@robertgarcia6923]

Very interesting & enlightening...thanks for sharing....hope to see more of this type of topics...

[@FOXGREEN]

Youe welcome 🙂

[@johnzaknich3979]

Cheers mate for the idiot's guide to joule creep, I think my IQ has just risen with all the math. Seriously though, I'm pretty sure some of the guys at my club are doing this, now I can argue the point with science and math. Cheers

[@FOXGREEN]

Thanks man. I can get into a lot more detail also there are other factors but this is good enough to give people a level of understanding that will benefit them going forward. 👍👍😁

[@drehstabenverbucher2273]

Wouldn't that mean that the Joule stay the same if you don't change the hop up? I always thought the Joule creep is due to the time of acceleration: the heavier the BB, the longer it is in the barrel and therefore, the longer it is being accelerated resulting in higher Joule through higher speed

[@FOXGREEN]

Not quite as I say in this video at the start there are many factors. If you chrono a gun with heavier bb and do t change the hop up you still get creep bit not near as much as you do when you adjust it. The main reason I explain in this video is this the main reason it's the same volume of air trying to pass a smaller point. It has to get past and to do so the pressure is increased as the mass if the bb is greater it tahe a larger volume of the air to push it out the barrel. Similar to what your said. But in truth is bloody complicated after that 🤣

[@TheRealRayzor]

Nice vid Kieran. Should it be also noted that the gun should be chrono'ed with hop off.. as shooting with the hop on reduces the fps/joule figures.

[@FOXGREEN]

That's actually an interesting one because some guns actually go up in fps if you apply a little fps as opposed to none and my SSG24 is actually like that. I get more FPS with the hop I use than without it. But as I said it varies from gun to gun this is something I should actually try figure out and make a video on also because it is very strange. 👍👍

[@nkanellopoulos00]

You are very wrong on that one. The majority of guns gain energy/speed by setting the hop properly. What you actually need to look out for is those that set too much hop hoping to choke the BB on the way out, then that will decrease fps/joule value out of the barrel

[@apachesmokewoundedsniper]

That was a great explanation mate

[@FOXGREEN]

Thanks your welcome 🙂

[@robertyoder9704]

So as of the 25 I have discovered a few weird facts about a part of joule creep that deal with grams and guns. To note I only used 2 pistols, an electric and a spring powered side note I don't have a crono but it all comes clear anyway. It was a little weird but being shot intentionally but as it were I chose a distance of about 12-15 feet I forgot to take measurements of the space but since space didn't change it worked out just fine(second side note)(2 shots were fired for each gram from both guns). So first to start was with the electric and the .12g, the impact area felt small but the pain/J's were range hi from 1-15 it sat at 10 for me, same gun at .20g the J's were still hi but didn't last as long the impact zone felt bigger as well to scale it was 8. Same gun again but with .25g the zone was bigger, so it felt, and as to my J's scale it felt like 4 and a half. Now switch to the spring, .12g, J's strong 11, then the .20g, J's went to 13, now for the .25g, the J's limit went higher, at about 16. I know it's a meter breaker but it happens. Any way so conclude, the findings are strange to me because the difference from electric to spring is "painfully" clear,and confusing, I would have thought the results would be reversed. But simply the spring sends a message and the electric let's you know nicely that you where hit. But as is I could guess that gbb pistols would fall some where between or higher still then the spring and electric. I can't explain why it went the way it did but that is my findings. I hope this is somewhat helpful.

[@FOXGREEN]

Thanks all information is very useful indeed so we appreciate you taking the time to post your findings 👍

[@thatspooneater7837]

Very informative answered my question on your latest video. Now to get shimming that spring 😂 thanks man 👍

[@FOXGREEN]

Always here to help. No problem man hope it goes well 😁👍👍

[@igorthehomelesscrackaddict5798]

FOX GREEN oh sorry I am referencing to the ssg24 rail hidden thread needed to disassemble the barrel from the rest of the gun as I'm trying to change the outer barrel to a shorter one

[@FOXGREEN]

You take if the top picatinny rail with and allen key and then that exposes the small grub stcew for the barrel underneath you need a small Allen key to take it out and then the barrel simply screws right off 👍

[@igorthehomelesscrackaddict5798]

FOX GREEN don't have the right Allen key but thank you for the info

[@FOXGREEN]

@@igorthehomelesscrackaddict5798 no problem!👍

[@RaufLKC]

Thanks for the attempt!

[@FOXGREEN]

Sorry it you dint understand I tired to simplify it . There is much more to it like the volume of the cylinder to barrel ratio. But the main factor is the one explained in this video I have found.

[@RaufLKC]

@@FOXGREEN Just joking a bit my friend! Got your point but still can't fully grasp the reason as a whole 😀

[@HatchetHavoc]

Great video man... 👌 Good explanation... Kept light for us skivvies to understand 😂 cheers man

[@FOXGREEN]

Man I am terrible at maths though even as an engineer 😂 I am pretty sure I made mistakes in this video also 😂 but it gets the point across all the same 👍😁

[@HatchetHavoc]

@@FOXGREEN definitely does dude ... If no one points it out it doesn't matter 😂😂

[@FOXGREEN]

@@HatchetHavoc 🤣

[@ALEX-xd7ko]

The real problem in my opinion is field owners seem to believe that only hpa can creep . It took me months and multiple show and tells to get the locals to understand that spring snipers creep as bad if not worse then any hpa . I got them to finally understand by taking an ssg 24 that was at 450 2.2 ? with .20bb and he was playing with it . I made him crono with his playing weight bb .48 and dude was shooting 3.8j.

[@FOXGREEN]

Yes all guns can do it and SSG is one of the worst for it. It's no myth it's easy to test at home and at least you took the time to explain it to others fair play 👍

[@jackkelly6251]

Very useful and easy to learn video. Out of curiosity, what FPS do you typically get with 0.3g BBs?

[@FOXGREEN]

I get around 273 fps on 1 joule with 0.3g bbs 👍

[@jackkelly6251]

FOX GREEN Not half bad, looking forward to playing lots over the summer, hopefully buying a sniper too

[@silkk_thecigarbrother]

That's good stuff man most big games here in the USA Chrono your gun for you using .32 BB's an that's the bb's i use for my DMR there joules for my gun is 2.1 joule my gun comes in at 2.0 Perfect for me thanks

[@FOXGREEN]

That's good to hear they are doing it the right way 👍

[@silkk_thecigarbrother]

FOX GREEN love yours videos Your game play Reviews and all that you're a good player But you also really smart 👍🏽

[@FOXGREEN]

@@silkk_thecigarbrother thanks your very kind man. I am not that smart though haha 🤣

[@silkk_thecigarbrother]

FOX GREEN Yeah Right lol.. You're a engineer c'mon now lol.

[@FOXGREEN]

@@silkk_thecigarbrother haha I am alright but I only know a lot about a little plenty of stuff I havent a clue about 🤣

[@chris_ackroyd]

Excellent starting point but maybe the reasoning for the speeding of the airflow does not make sense to me: The area reduction is only in a very short section and opens up again after? So therefore wouldn’t the speed then slow down?

[@FOXGREEN]

Nope its the same as when you pinch a garden hose the smaller area forces the water to spray out faster even though your are only squeezing a small section of it also. It's just flow mechanics.

[@chris_ackroyd]

@@FOXGREEN agree - if you pinch a hose at the outlet then the smaller area (same flow) means faster speed because the volume can increase as it can pull air form the surroundings…but if you pinch a hose half way along all that happens is a reduction in volume as the is no way to increase the air volume?

[@ArcticFrenzy]

I'm having school flash backs and the classic physical pain that come with doing maths D: still a good video and I'm thankful you explained it

[@FOXGREEN]

🤣 sorry for those flash backs man 😂

[@ArcticFrenzy]

@@FOXGREEN all good XD

[@flyinghotdog7270]

Great video man. my ssg joule creeps like bitch! As you said not alot of people actually know what or why with joule creep. Great informative video.

[@Eitinsky]

Interesting 👍. Good tips

[@peterlustig9103]

Does the barrel renght has an impact on Joule creep? And if yes, how?

[@FOXGREEN]

Not on joule creep just on FPS of you install a longer barrel you get more fps is all

[@santi_super_stunts2573]

So like do people take advantage of joule creep? For example ignoring the fact that heavier bbs travel farther effected less by wind and travel through bushes better , is that why ppl use heavy rounds in snipers? For the higher fps? How much does it really effect fps. I’m using 0.36 in my novsritch ssp1 green gas and people tell me it hurts , idk if they are just being wimpy or it hurts more than it should. Ill gladly go back to 0.25 if my 36 is shooting a little too hot. I just had 36 I never used so I decided to try it

[@FOXGREEN]

I have my guns tuned to 1 joule using heavy 0.32g bbs beacuse if I tuned them to 1 joule using 0.2g bbs and then put 0.32's in it it would joule creep up to 1.3 joules. So the way I do it I always make sure I am getting one joule with the heaviest bb I am using so my gun will never ever be hot. But besides this heavier bbs will go further as they are travelling slower the wind resistance on them is far less. Heavier objects once moving keep their energy for longer than light objects. So a sniper use heavy bb mostly for range and because wind is less likely to push them off target plus they will still have enough energy down range to punch through bushes also. Sites that chromo based on fps or just chrono guns on 0.2g light weight bbs are leaving themselves wide open to hot riffs and people are exploiting it. Its dangerous and site owners should instead be chrinoing guns with heavy bbs and on joules only that will rule out all people with hot riffs. Set your chrono to 0.36 bb and see if it's over 1 joule if it's nit don't worry about it. The heavy bbs are just keeping there energy down range it's similar to getting shot up close with a 0.2g bb at 1 joule is all they are expirencing.

[@Stillsz75]

Great explanation....thanks..

[@FOXGREEN]

No problem man 👍😎

[@Stuartscott171]

Hey pal, great informative video, explains a lot how this all works but what is your opinion on how an airsoft site should chrono guns? I know every site has their rules which may be followed wether you like them or not but when a rule comes down to being governed by law I’ve had a number of places all chrono differently. Some sites ask you which weight of bb you use and then set their chrono for that weight, some sites use their own .2g bb and then take your hop all the way off which isn’t only an inconvenience after having your hop set perfectly to have a straight and long flight path but I don’t feel that this is right?

[@FOXGREEN]

There is only one way that atually works where you can stop all forms if cheating and it goes like this. Basically a site should chrono in joules to the countries legal limit the site should use theirown bb's which should be the highest weight bbs possible. This rules out cheaters who say they have a certain weight bb in their mag when they actually have heavier and appear under the law, it rules out joule creep i.e. people chroning with light bbs versus the heavier one that they actually use when playing the game and it also rules out fps no countries laws are dictated by. All countries have legal limits governed by joules beacuse they are all legally govern by joules beacuse they fully take into account the weight and speed of a projectile giving its total force on impact not just its speed, which is fps, usuless on it's own. I mentioned this best way of testing on my video and now our local site runs this rule. They have found out multiple people over the limit since using it! It's also good to make sure your gun passes both with hop up on and off as some guns shoot hotter with them on and some shoot hotter with them off. Test you gear thoroughly. I hope this helps.

[@Stuartscott171]

Thanks for the info. I only hope that all sites learn this valuable information.

[@emilmadsen8972]

It's basically like a car going 60 hitting a wall and a semi truck going 60 and hitting a wall

[@Stillsz75]

Ok, I know you are aloud 1 joule for your field. What spring , bb weight, and fps do you have for ssg24? I currently have a well mb03( vsr10 ) clone. With .20gr bb's it's over powered. I got the gun for 71 bucks shipped. Seems like the spring is not stock. The spring tension is really strong . It's not the bolt or the cylinder they smooth with no wear. Just wondering if had upgraded spring put in. But my goal is to get full thrust upgrade and go from there...

[@FOXGREEN]

I bought a m110 spring which is overpowered for 1 jouke but cut a coil to get the power just right. I use 0.3g BLS bbs so that shoots the bbs at 260 fps which is 0.98 of a joule roughly

[@Stillsz75]

@@FOXGREEN that's really good. Your shots are excellent with that set up...the closest field to me allows 500fps @ .02's . Just got to find someone with a chronograph or buy one. I know that all the videos I seen on stock mb03s were over 450fps..

[@toothlessdevildog80]

One thing that definitely "clicked" was the "AH-HA" moment when you explained that you are an engineer . I wondered why you seemed more intelligent than most youtube producers , it is because you are :)

[@FOXGREEN]

Thanks man I dont know about that 😎👍

[@toothlessdevildog80]

@@FOXGREEN At least in my opinion (the only one that counts just ask my wife , she will ... laugh hysterically) . Seriously though thanks for the video now I can just point any joule creep questions to your video. Awesomely explained and broken down to a good level .

[@ALEX-xd7ko]

Here they make hpa crono with .32 i still argue this as from .32 to .45 you can easily see a .75-1 j increase . I make all snipers , dmr, hpa , crono with .40 unless i know them well and know they will actually play with what they crono

[@FOXGREEN]

Good idea no harm to be safe 👍

[@igorthehomelesscrackaddict5798]

What did you do to remove the hidden thread screw to disassemble the barrel from cylinder ? Thanks

[@FOXGREEN]

In which gun are you referring to I am a bit confused I dont use any gun in this video?

[@stigmau5]

Quick math 😉 great insightful video man 😃.

[@FOXGREEN]

Haha I am suck a nerd 😂

[@stigmau5]

FOX GREEN A nerd who knows joule creep 😂

[@FOXGREEN]

@@stigmau5 😂

[@mateuszszajner3547]

So to count I need to now F=acceleration*mass and i wil get J right?

[@FOXGREEN]

Go to 3:50 in the video thats equation is the correct equation to work out joule so use that. The F=MxA is too simple so use the other one I was using it to explain was all.

[@MercutioUK2006]

"Or people cheating the chrono as creep happens with more efficiency with HPA guns.

[@vashp2]

Thanks for this. Now I can prove I was right about the Q formula.

[@FOXGREEN]

No problem man!

[@chemapc]

Sorry doesn't sound right to me. Let me explain myself: 1.When you apply hop up the fps goes down not up. I think it is because the bb is stuck under the hop up as you push on the rubber, some air is lost around the bb until it finally flies free. The energy is not lost, its just changed to heat, one can see that on the hop up rubber temp. 2.When doing chrono hopup should be at lowest setting anyways, because of point 1, so your theory is invalid. 3.The energy accumulated by the bb is the key.

[@FOXGREEN]

When I turn my hopup up to spin a heavier bb enough for a flat trajectory FPS goes up. If I apply excessive hop up more than I need it reaches a point where it slows the bb down and too much the bb won't come out. The key here is you adjust the hop up only slightly up to spin the bb and thats not enough to slow it down its actually speeds it up due to the air trying to get past a smaller cross sectional area. I tested this loads and loads. Applying too much hop slows the bb as it is all lost due to excessive friction. Its not theory its from lots of testing. This is just one factor there is far more complicated details around the volume of cylinder to barrel ratio that accounts for joule creep also.

[@kehoe0069]

what mod did you do to your ssg to get it to chrono at 1 joule with a .36gbb?

[@FOXGREEN]

I use 0.3 or 0.32 not 0.36 all I did was cut cut or shim the spring with washers to get the desired joules and chrono it repeatedly until it's perfect.

[@kehoe0069]

cool did you cut the m9 spring down? and shim that?@@FOXGREEN

[@FOXGREEN]

@@kehoe0069 I started with an m110 spring that was over powered and cut that down bit by bit

[@NepaAirsoft]

328fps (1j w/.20s) = 267fps (1j w/.30s) I Chrono in joules all the time on the field.

[@FOXGREEN]

Yes that's right 👍

[@NepaAirsoft]

@@FOXGREEN - better to be under then over, right?

[@FOXGREEN]

@@NepaAirsoft always man. It's not worth getting in trouble over such a simple thing 👍👍

[@NepaAirsoft]

@@FOXGREEN - My one teammate said it best when asked about our 400 FPS field limit. He said, "400 is a limit, not a goal."

[@marabu1977]

Un/Fortunately I live in world where these "laws" does not work. :) My gun is setup and these are the measured results: - 0,36g appropriate hop => 2,55J - 0,43g same hop => 2,5J - 0,43g appropriate hop(maybe two clicks more) => 2,48J - 0,36g same hop => 2,4J I am not saying that joule creep does not exist but it is only in few specific cases. Issues are 1) hop does not just reduce the theoretical area but also slow down the BB 2) reducing the area can work on water (hydraulics) but air is easily compressible so the influence will be negligible 3) example with garden hose works with constant flow but not so much with single injection in case of airsoft guns

[@mw2mastersash]

i'm guessing until the law changes its just a loop hole...also whats to stop people for using a .3gr bb with a fully opened hopup to stop the jule creep and i'm also sure that if law was to change and they scraped the .2gr bb 95% of peoples guns would be breaking the law...its a bit of a touchie subject....does law need to be changed to scrap the .2gr bb or to scrap using heaver bbs??

[@FOXGREEN]

Hmm I think rules for how guns are tested should change such as guns should be tested at sites using the sites bbs and they should be heavy bbs so they can say for sure that the gun is safe and only the joules should be looked at. That way I think you can rule out accidents fully but yes it is a touchy subject 😅

[@johnsosta621]

You give an example of water going faster from a hose when its restricted, what you fail to mention is that the hose is pushing the water constantly over a period of time, an airsoft is not pushing the BB from an infinite source, it is expelling and metered amount of energy , therefore the BB will not accelerate more.

[@FOXGREEN]

If you take a set amount of air in this case the air volume of the cylinder and you push that air out through a 10mm hole with the same force from the same size spring it will come out at a certain speed. You repeat that test with a 5 mm hole the air comes out at an accelerated speed. That's what is happening. It's simple physics. I didnt fail to explain it you failed to understand it. The airsoft gun is pushing the air out at a constant force as the spring provides that force.

[@johnsosta621]

​@@FOXGREEN You say simple physics, in simple Physics you explore all possibilities before you come to a conclusion and then call is as the truth, in this case all possibilities that can affect the velocity of the BB have not been considered, You say when a gas is pushed through a hole it accelerates, yes it does but the hole that its pushed through is the same for both BBs, so which hole are you talking about ?. There are other factors that affect the velocity of different BBs much more drastically than what you are saying, but you only focus on what you think is causing the velocity hike.

[@jimdad24]

Just remember your gun must be safe on all bb weights not just the one you intend on using

[@FOXGREEN]

Yes that's true. But the heavier the worse it gets. So as long as you meet the regs joule wise on the weight you actually use your all good. The law is the joule limit nothing else. If you dont exceed that then your 👌 this video it to raise awareness to people who dont realise they could be running hot guns at times bu cronoing on a light we9ght bb and then changing up to a heavy bb after 👍

[@jimdad24]

@@FOXGREEN See you have got to be careful because some guys will bring up the power on their weapon say to fire a .3g bb at a joule ( because not all guns joule creep) and in doing so are breaking the law by having a weapon that can fire a projectile over the joule limit Yes I agree that some not all guns can joule creep and the more awareness about this is better

[@ALEX-xd7ko]

Oh 100% will cry that hpa is j creeping

[@SwApPyY]

Love that you bring the subject up, but it's alot more complicated then this and what you described in the video (why joule creep occurres) is only half true, I think you should have "dumbed the video down" more or explain everything. Because this is not easy or good information for beginners. Love your videos, just trying to give productive feedback, send me a message if you would like to hear more input or discuss further as I do agree this is a very important topic. BR Simon

[@FOXGREEN]

Thanks man yes it is far more complicated but I feel this is basic enough for peopl to at least get a small appreciation of what's going on. I could maybe have tried to make it a bit easier to understand but I am not sure how much value I would have gotten buy doing that. Thank you for your very valued feedback and help. I always appreciate it 👍😎

[@bad_boyz6824]

It's been a while

[@FOXGREEN]

Sorry super busy with work 👍 I had a new gameplay up last week also check it out👍

[@bad_boyz6824]

Nah it's ok I still watch tho I just don't really comment

[@ghostwalkerairsofttech1947]

Joule creep is simply explained as extended force exertion. The longer the bb stays in the barrel the more energy build up behind it takes place. Think of it like a shotgun shell with slow burning powder in it. The longer time it takes for that energy to build up to force the wadding out of it the more energy it creates for the projectiles. This is why we volume match cylinders to barrels so that we can use specific weight projectiles to gain various performance characteristics. Chrono with FPS limits is pure BS!!

[@FOXGREEN]

Thanks man I agree especially chrono with FPS haha xD

[@DMKpop]

Sorry, but your explanation is wrong, to prove this, experiment with different BB weights without adjusting hop up setting. Actual reason is because lower fps of heavier bb, so it spends more time being accelerated by same force as with lighter bb in the barrel.

[@FOXGREEN]

My explanation is not wrong its one of a few factors that cause joule creep as I mention in the video. Voulme ratio of cylinder to barrel is also another factor that contributes.

[@DMKpop]

@@FOXGREEN The factor that you have mentioned have marginal effect comparing to time delta of force applied. Volume ratio is not a factor of joule creep itself, it only affects how much joule creep you'll have.

[@Elizareads]

​@@DMKpop I mostly agree with you, and whilst this video does a good job of alerting people to joule creep, it's kind of missed the more fundamental physical reason behind joule creep. The real experiment one should do is to use the SAME bb weight, with different hop up settings. You'll typically find more hop up means more friction, hence less FPS, hence less energy. There will maybe be a small point of the tuning where the increased mechanical impedance from the hop up bucking actually increases FPS, but it's *absolutely* not the main reason joule creep occurs. The real situation with joule creep is actually very analogous to impedance matching, and optimal power transfer in electrical circuits en.wikipedia.org/wiki/Maximum_power_transfer_theorem You could actually frame the above for gas guns as saying that maximum power transfer to the BB occurs when the pressure behind the BB matches the total pressure of drop of the system due to leaking etc (ie, when the source and load resistance/impedance are matched). To take it to an extreme, if you had a perfect airseal, and perfect BB to barrel fit, your "ideal" BB weight for maximum power transfer would be that largest weight you could run before your gun explodes. But to give a simpler analogy than electricity, imagine trying to hit a ping pong ball with a cricket bat, vs hitting a cricket ball with a cricket bat: which feels easier? A cricket bat is heavy, and requires energy to swing, and most of that energy is usually lost when someone tries to hit the ping pong ball. Whereas less energy is lost when someone puts the same energy into trying to hit a cricket ball with a cricket bat: probably why it feels like a lot less effort. What's going on there is that the ping pong ball is light and flimsy, and gives way very quickly (ie, it has low mechnical impedance). As such, it doesn't maintain contact with the bat for very long, and so most of the energy of you swinging it doesn't end up in the ball. Whereas the cricket ball is much heavier, and will even compress the bat slightly, leading to a more sustained contact, and greater energy transfer. Now on to airsoft, with your light 0.2g bbs, compared to heavier 0.4g bbs, as soon as the gas is released, the 0.2s will fly out the barrel sooner than the 0.4s, and whilst they will be going faster initially, they have absorbed less energy from the gas release. The point is that the gas expansion is not a totally instantaneous occurrence: it happens over a short but non-zero length of time, and there will be an ideal bb weight for getting optimal power transfer: and that weight is certainly much higher than 0.2g. TL;DR impedance is essential for power transfer in any physical system, including airsoft guns, and heavier bbs have higher mechanical impedance than lighter ones. That's genuinely the fundamental reason behind joule creep.