Fps raise. Let's get it DONE

[Teo]

What I mainly want is a fps raise for snipers. That should be allowed. The other reason for the fps raise is that if your gun comes stock with an fps of 350 etc. you will have to spend more money getting it downgraded.

 

[Unrustle_Thine_Jimmies]

Well,most retailers have the guns downgraded by the wholesalers before they are imported. A lot of companies also have guns made for the Japanese market with 1J spring out of the factory

As much as I'd like an increase of FPS for Sniper rifles,I'm afraid that we'll suddenly have a massive surge of pseudo-snipers with stock china made rifles running about being useless. Right now a lot of people buy sniper rifles,say 'dis am shit,not enuff dakka' and quit,mainly people who really dedicate themselves to upgrading and the playstyle actually stay in the role.

 

[Monty]

A sniper doesn't necessarily need high FPS.

Good hop up unit > FPS.

 

[toothpick-NL]

like monty says. a sniper need op FPS up but UP-grades.

a upgraded aeg with max 360 FPS can shoot further than a basic bolt action with 500FPS.

i saw it and the sniper calling that the aeg user was cheating and having tomucht FPS becaus AEG shoots bolt sniper down but bolt sniper couln't hit aeg person

:lol:

 

[Unrustle_Thine_Jimmies]

Bolt action rifles are more for the playstyle and they are generally easier to upgrade to perform well,most having super simple and quick disassembly and design allowing you to tune it easily. That said,you can get an AEG having the performance of a bolt action rifles and have the advantage of having 40RPS,but it's more rewarding and fun with a boltie,with an AEG you have to do a fair bit of gearbox tuning to get it running quietly and having instant response.

I've been using my VSR for 3 years now and I still get a childish shit eating grin when I cock the gun because bolting the gun dramatically makes you feel cool

 

[toothpick-NL]

a ateammate of us spent like €500,- on upgrade parts but he is shooting were he is aiming.

its pretty scary if you see what he can hit with his bolt. but luckely he's on my team

 

[Ian_Gere]

Joule Creep, like Suckback, is a theory which makes complete sense when explained generally, but in actual fact, once the maths are applied it starts to look a bit different.

100m/s = 328fps = 1J w/ 0.2g BB

81.62544m/s = 267.8fps w/ 0.3g BB = 1J also

455mm barrel = 0.45m / 100m/s = 0.0045s time of a 0.2g BB in the barrel

455mm barrel = 0.45m / 81.62544m/s = 0.0055129898291463s time of a 0.3g BB in the barrel

Difference = 0.0010129898291463s

A 0.3g BB spends approx 1 millisecond longer than a 0.2g BB in an AK barrel

Now I'm not familiar with the maths which describe how much energy is transmitted by expanding air but I do know that, just like sound, it is exponential. So if the force at arbitrary distance A from the point of origin is X, at distance 2A the force is the square root of X. But also the speed of the BB actually starts at 0m/s so what we really need is to know how to calculate the acceleration which the force imparts... engineers? We are talking about what happens at the very end of the time in the barrel though and we do know the final velocity, so I think we can make educated guesses at what is happening just before the point in time at which the velocity is measured accurately enough for this discussion.

But leaving that aside, instead lets consider 0.2g BB's in an M4

(363mm barrel = 0.36m / 100m/s = 0.0036s) ^(455mm barrel = 0.45m / 100m/s = 0.0045s)

Difference = 0.0009

If you put the same cylinder and spring in an M4 that you put in an AK, do you expect to see a difference in performance that translates into a usable advantage in play? No. And that is an approximately equal time difference as that caused by the difference in weights.

Ipso facto it's bollocks.


Yeah good hop... bla bla bla... Consider this:

Assuming the site has the common limit of 350FPS

Gun 1 has hop unit & rubber A and spring X - it fires @315FPS and gets a 0.6m grouping at 50m

Gun 2 has hop unit & rubber B and spring Y - it fires @345FPS and gets a 0.6m grouping at 50m

Gun 3 is yours to build. You can choose either hop and either spring. Do you choose A & Y or are you mental?

 

[Unrustle_Thine_Jimmies]

I've dug up some threads on airsoft mechanics,which is probably the best place for airsoft physics + technical stuff to explain joule creep in a bit higher detail. I recommend to read them fully.

http://forums.airsoftmechanics.com/index.php?topic=11308.msg133390#msg133390

http://forums.airsoftmechanics.com/index.php?topic=11161.0

It's hard to use maths to calculate joule creep as there are so many factors,as pistons don't expel the air volume in the cylinder instantly. Calculating gradual expanding air and how it affects a load accelerating down a cylinder which also has blow by depending on the bore is also hard enough,don't forget to factor in compression quality and compression rate and all that stuff.

Using the old fashioned method of jamming in different parts,tuning them appropriately and testing to see which set gives the best results is probably the best method of finding out how joule creepy your gun is.

Here's a post by hunterseeker5,a guy generally regarded to be pretty experienced in matters like this:

--------------------------------------

Lawlz r/airsoft. What will they think of next?

________________________________________________________________________
Quote from: AcidReaper on 26-11-2013, 03:06:43
This is a direct quote from one of the comments on reddit.

"It may be generally known but it's dead wrong. Experimental results show just the opposite. This guy in the linked article shot himself in the arm at point blank range with .12g, .20g, .25g and .28g BBs from the same gun, with the same spring. The .12g BB did the most damage. The pictures speak for themselves.
Joule creep is nothing but a chairsofter's pipe dream apparently. Real world BB wounds on bare flesh are not a pure function of Joules. There is something more complex involved."

http://www.nationalairsoftmagazine.com/ouch.html

Is there any suggestions on a better way to explain it?
_______________________________________________________________________


What are we arguing here exactly? Because I'm seeing separate issues: tissue damage vs. KE shift.


Regarding tissue damage, the point of that article was to show bbs with effectively identical kinetic energies impacting skin. Its demonstrating that, all else being equal, its velocity that does the superficial tissue damage. This is because BBs don't have much energy, even our insane high power guns have very little energy, so the higher velocity the round the higher the impulse force on just that top layer of skin and thus it destroys more capillaries and appears to be a worse wound. Thats that theory. There are three problems invoking it in this argument though: 1) all the rounds are intended to have roughly the same kinetic energy, 2) as you can see from sites like the ATP, higher mass rounds retain their kinetic energy better, and eventually not only overtake their higher muzzle velocity lower mass counterparts, they end up with a higher velocity than them as well (ref. http://mackila.com/airsoft/ATP/07-b-01.htm), and 3) I don't think anyone is trying to make the point that the reason they want joule creep, as its come to be known, is to @#*! people's #%$! up at point blank range.

So in regards to actual KE increases, I should start by saying not all guns display it to any significant degree. In fact, unless you specifically tuned for it, its existence is an indication you likely screwed something up with your build because it has negative effects on accuracy as a result of muzzle turbulence. Achieving it in an AEG is relatively simple, drop a 200mm barrel in your gun and a full cylinder. Tada, unless you're at fringe high power levels, your gun will see increased power with higher mass ammo. It only really came into the public eye as of late though because with P*s its so easy to inadvertently do, more and more people started "discovering" it for themselves. The point of doing it, intentionally, isn't to @#*! people up, its to gain an advantage; this is the same with all tuning. If you can be field legal (400fps with .2s) why wouldn't you take a 20% power gain with your preferred .3s? You're still field legal, and now you have a serious range advantage.


In regards to field rules to adapt to this: field restrictions are by the Joule, end of story. Your gun with your ammo must be X Joules (usually 1.5 for most fields) Of course this would require the chrono monkeys to have two brain cells to rub together, something which might be a bit of a stretch unfortunately, but otherwise you're stuck with things the way they are. Alternately you could run some experiments to determine maximum likely KE creep, and adjust the limit with .2s downward so that what you consider to be "safe" is within the limits techs running over-volumed guns will be able to achieve with their ammo. That way it preserves our advantage as the superior species, while keeping everyone "safe."

 

[CaptainSwoop]

I call bollocks on 'Joule Creep' being a factor in range. We are talking about fractions of a gram.

Seems to me it's as much psychological as anything, you aren't adding any more energy.

 

[Unrustle_Thine_Jimmies]

When I say range,I mean effective range,as in range you can actually use. Effective range is a combination of how far your gun can fling the BB and how accurate it is. Your BB may fly a long distance but have an uneven trajectory. it may fly a long distance but it may curve off back to Japan to the injection molding machine it came from.

Heavier BBs retain kinetic energy better than lighter BBs. Heavier weights are more resistant to wind and are more stable. Kinetic energy is also a factor on BB flight.

Joule creep exists,there's no denying that. How effective it is really varies on how well your gun is tuned,and it's traits(Cylinder to barrel volume ratio,all that craic)

Second post in this thread shows chrono results between .2g BBs and .4g BBs.

http://www.airsoftsniperforum.com/32-general-sniper-talk/9995-energy-creep.html

also check this out too,the airsoft trajectory project,Section VII shows how heavier bbs,with a greater Kinetic energy fly compared to lighter weights.

http://mackila.com/airsoft/atp/

 

[CaptainSwoop]

We are still only talking about fractions of a gram though

 

[Ian_Gere]

Well Alex, I commend your diligence, but I can't read those Airsoft Mechanic links because I'm not a member, but then again, as I said at the top of my previous, Joule Creep does make perfect sense when explained generally. You're also right that the maths involved is extremely complex, not just describing expanding air mass X in volume Y exerts force Z, but as you say the air is not sealed behind the BB, but also there will be a slightly different friction coefficient between barrel and various makes of BB, although how fast the air exits the cylinder does not actually matter because, according to Pascal, the system, ie cylinder, nozzle & barrel, has to be treated as a single volume against which the compressed air presses with equal force all over its inner surface. But also consider that the higher the pressure inside the system, the worse the leakage will be.

For anyone else following this discussion, in terms of physics the correct way to understand the issue is that once the piston is released the volume of the system changes at a different rate for different weights of BB, so the internal pressure at any given moment is also different, and because the system will eventually only contain between approx 2/3rds and 1/2 of the mass of air (depending on cylinder/barrel ratio and leakage), that air will continue expanding until the BB has left the muzzle. Hence we are attempting to determine whether the fact that, at any given moment of time after the piston is released, while either BB is still in the barrel, say 1ms, the slower moving one will probably be under slightly more pressure, since the volume behind it is less but the mass of air approximately equal (not equal since the higher pressure volume leaks more), actually results in a noticeable shooting advantage or whether it is just, to nerds like me, an interesting phenomenon which translates into bugger all irl.

To put the subject to bed once and for all we would need the results of a statistically significant number of experiments where both the instants of piston release and of muzzle exit were recorded alongside spring strength, muzzle velocity, and barrel length, so we could work out an accurate average acceleration of fired BB's (why not just record the BB weight and distance of trajectory as well? Because ballistics is even more complex than ordinary fluid dynamics, so, in the absence of actually measuring the strike force of thousands of different BB weights fired from hundreds of different guns, we need a figure which is applicable to real world situations as well as lab conditions). From that we could work out fairly accurately the volume and hence pressure / time and thus the total amount of energy transmitted using calculus.

My position however is that we can cut through the most difficult maths and that, without reliable explanation by someone/s who do fully understand all this, the complexity of the subject actually does nothing to aid our understanding, in fact exactly the opposite, because since we must admit that we do not know the ins and outs of a duck's arse about the subject, we are being asked to accept that we do not know enough to make a useful real world estimate, which, I submit, is not the case. My above quick and dirty calculations do not take acceleration into account so the difference in times spent in barrel by different BB weights cannot be relied upon as an absolute figure, but we can say that since the BB starts at rest and reaches the muzzle doing, say, 328FPS, then if we did have an acceleration figure to work with we would discover that it takes longer for the BB to travel, say 455mm, than simply dividing that distance by the velocity, 100m/s, and coming up with 0.0045s.

We know that the biggest single variable is the BB weight and everything else remains approximately the same, so the crucial understanding is to realise that whatever the actual figures are, the ratio between the unknown real times in barrel for 0.2g and 0.3g BB's will be the same as in the Q&D calculations, since we are working with known velocities, i.e.

0.0045s (the time taken for a 0.2g BB to travel 455mm at 100m/s)

/

0.0055129898291463s (the time taken for a 0.3g BB to travel 455mm at 81.62544m/s)

= 0.816 (3dp)

So whatever the real times are, the 0.2g one will be approx 81.6% of the 0.3g one.

What matters for the estimate though is the ratio of the difference between whatever the real times are in ms and those times themselves, which we know will not differ by more than 20%, and we also know must be greater than my Q&D results, so...

≤0.0010129898291463s / >0.0055129898291463s = <0.1837459999999971

...or, in plain English, what we are talking about is the energy which can be transmitted in less than the last 18% of the total time in the barrel, bearing in mind that during this time the force transmitting the energy is exponentially less than during the previous 80-odd% of the time.

Thing is, all of that goes on kind of subconsciously... as I said above, you only need to consider the difference between barrel lengths. Yeah, there is a difference, but it isn't significant enough to affect play.

 

[M_P]

We are still only talking about fractions of a gram though

to be honest that's not a great argument against it. A .3 is much more accurate than a .2 and still a fraction of a gram, little things do make big differences.

 

[Ian_Gere]

to be honest that's not a great argument against it. A .3 is much more accurate than a .2 and still a fraction of a gram, little things do make big differences.

yeah, it's not fractions of weight we need to look at, it's fractions of time, fractions of milliseconds even...

 

[CaptainSwoop]

Has anyone actually done any controlled testing of different weights? a gun in a bench rest and several hundred rounds of each weight shot at a target at various rages?

 

[M_P]

Not personally but you don't need to to see large differences, you can see it yourself by simply shooting a gun with various different weights.

 

[Ian_Gere]

ErThose bench tests must have been done to find out how safe/unsafe airsoft is when using typical eyepro, otherwise nobody would insure airsoft sites. I'd want to know whether the tests were done using something like a lab high pressure air line so the pressure behind the BB could be adjusted exactly, or simply using real guns. Also whether anyone involved was an airsofter because it seems to me that, if not, they could have forgotten one very important thing which we haven't considered either.

There is something which proves beyond a shadow of a doubt that Joule Creep has no effect whatsoever on actual airsoft shots, even if the maths which I was unable to fill in above did somehow come up with a figure that is real world significant, which I think is impossible but let's just say, and that is the fact that it takes more hop up to lift heavier BB's than lighter and the more hop is turned on, ie the more friction applied to the BB, the slower the slower it goes, ie less of its energy is conserved as momentum because it has been lost as heat and sound...

 

[CaptainSwoop]

I can see how extra weight could improve accuracy down range as any wind gusts wiil have less effect but again we are talking about tiny fractions of a gram in weight.

 

[M_P]

I can see how extra weight could improve accuracy down range as any wind gusts wiil have less effect but again we are talking about tiny fractions of a gram in weight.

Get a 500 fps rifle on a still day and fire a .2 and a .4, the difference is very noticeable- It doesn't matter how small the difference in mass of the projectile is, it has an impact regardless. Otherwise everyone would just use .12s.

 

[Airsoft-Ed]

Personally, having used one specific gun for an exceedingly long time using the same set up on the brink of the fps limits, I do believe that Joule Creep is real, I have known guns fire at very close to the limit on a .2 that when chrono'd with .25s are shooting quite a noticable amount higher than the conversion charts state it ought to be.

My ICS L85 was firing at more or less 365 on the dot on the medium tension setting, which is perfect for Skirmish Airsoft's 368 limit, but when visiting most other places that have a 350 limit, I'd have to lower the tension a notch on the spring, which generally put me around the 345 mark.

According to the conversion charts, 350fps on a .2 equates to about 313fps with a .25, but I would see readings in the region of 325/330 with .25s with my L85 - I was losing barely 20fps when I should have been losing around 35/40.

I've brought up the point before that barrel bore plays a part in how conversion charts work, and I think joule creep is basically the same effect happening, but exaggerated. You do gain power by using heavier ammo because more air acts on the shot than it does with a lighter round.

In a tightbore less air can get around the BB, so more of it gets used faster, so to speak, and lighter BBs therefore obviously end up with a higher muzzle velocity.

Put heavier BBs in and there's the same space around the BB for the air to get past, which isn't a lot. So instead of losing the 40fps you lose from a .05mm barrel, in a .01 you instead only lose about 20fps because far less air gets the chance to escape around the bb.

I firmly believe based on personal experience that joule creep does exist and it exists to a noticeable enough level to make use of it.

Additionally, on the topic of effective range I can also say from experience that when you're used to 365fps and you have to drop down to 345, when working at the extent of your effective range, which realistically speaking for me was around 45m, 20fps is the difference between hitting someone in 5 shots, and hitting them in 15.

Obviously the shooter's familiarity will have something to do with it, someone that's used to 345fps will probably be able to shoot better than I can as someone who's used to 20fps more than that, but the fact is, your actual range does change by enough to notice it, and your effective range drops off significantly more than you'd have thought.

Visiting Anzio for the first time I had to deal with my gun being what I felt had become unsuitable because the 20fps power drop changed it's performance characteristics that much that I had to play differently, aim higher, lead further, not engage until targets were quite significantly closer.

If you play as much as I do and you have a gun with variable fps so you can ensure every other factor is the same, you will definitely notice a difference regarding fps and range, and you can physically observe joule creep happening if you have a chrono.