Do heavier bb's hurt more? A test.

CrazyRabbit

http://unconventional-airsoft.com/2008/11/13/a-case-for-using-12g-bbs-in-close-quarters/

Some interesting results. Perhaps 0.12g bb's are best for CQB. It's also explains how hits from some AEG's appear to sting more than others (it's owner was using .25's or higher???)

I know the test above is not perfect science, but it does appear to have merit.

kevteljeur

Great link, Mr Rabbit. It's interesting alright, and a valid way to run the test. It's been observed before that .20g bbs are rubbish in undergrowth, while .25g can travel through. I've also noticed that sub-1J .25g bbs can feel in practice (and at range) like they're substantially over-powered and leave a serious mark, because of the heavier impact. I favour them for these benefits and the accuracy.*

It's food for thought alright; banning full-auto for CQB might be the wrong answer for the right problem after all...



* As if I know what I'm talking about.

OzCam

I doubt it. The figures don't add up.

Even at the full 100m/s velocity, that's still only 1.25J. Since much human perception is logarithmic, a 20% increase is pretty insignificant. I would guess that the close range would have much more to do with it, since far less of the BB's energy is lost to atmospheric drag compared to a 20 to 30m engagement.

And, more importantly, cheap .12g BBS are likely to damage your gun, and that's if they feed at all.

PS: putting my safety officer's cap on for a second, the testing the chap did was valid, and pretty good, but the raw physics of the impact and the target's perception of the impact are two different things (as the tester noted). Since all airsoft guns in Ireland have to clock under 100m/s by law*, and since everyone should be wearing face protection in CQB anyway, I don't consider that the reduction from 1J to 0.6J is really worth the effort. Below a certain point, halving the hazard doesn't get you double the benefit. I'm willing to be convinced otherwise, but I don't see it.

Dex?

* let's not get into the nitpicky technical arguments, you know what I mean here.

Hivemind187

Simply put;

If the output power of the spring and cylinder is 1 joule then the energy imparted to any projectile will be 1 joule (yes, this is simplified).

0.12g BB's will move faster due to their lower mass.
0.25g BB's will move slower but retain more energy due to their higher mass.

A 0.25g BB will therefore likely have more retained energy upon impact with a surface than a 0.12g BB. This does mean that they may indeed "hurt more" due to the increased shedding of energy on skin and the corresponding increased "pain" singals sent by the nerves to the brain.

It should be noted that this does not make either of them more or less "dangerous" since the energy required at point of impact to penetrate even the weakest tissues isin excess of 1.35j.

Therefore, regardless of what weight BB you are using you should not be able to cause significant harm to anyone (provided they arent thick enough to grin down the barrel of a G36!).

The so-called "Full Auto ban" in CQB is not to prevent serious injury from fire. It is to curb the accidents caused by blind firing morons and cater to the needs of our more "sensitive" players (i.e. whingers who wear a t-shirt to CQB and then complain that "getting shot stings like the dickens!").

Further notes on the tests;

Putty is a lousy substance to test anything with. It's surface tension and physical resistance will vary depending on heat, numnber of shocks it has already had, humidity etc So the readings are unreliable at best.

"Floral Foam" is also not much good when attempting to link BB weight to potential injury. It's surface cells are far weaker than those below them and a such reacts more like sand or earth when struck. Skin does not operate this way.

Now I'm not denying that the heavier BB's will impart more energy upon impact but I will challenge the assertion that a device producing 1joule of energy from the mechanism is going to be capable of causing damage of any significant kind in contradiction of the established 1.35j of force required for a penetrating wound.

Masada

I think its perfectly reasonable to assume heavier BB's will "hurt" more, or transfer more energy.
Put simply, it takes less power to fire a light BB (forgetting the whole joules thing for a minute), so it would in theory take less to deflect it, surely?

TheDoc

I've made my feelings clear about CQB and the full auto/semi auto thing.

I just prefer semi because its more skillful. Yes there is normally blind fire galore. But semi is alot more skillfull and I think makes for better CQB encounters. Plus, not to generalise, the word "overkill" is completely lacking from most peoples heads in CQB scenarios. I tend to be generous and burst fire a couple of BB's, instead of what seems to be the mass following, wait for your target to curl into a ball screaming then stop.

Also, if I'm not mistaken, semi auto would be used in "real" CQB scenarios ( CT units moving through occupied buildings) Thats open to correction though.

I'll take pain as much as anyone and I'll dish it too, but I just think its more skillfull and fun using semi.

As regards the weight of BB's, I've done a little home test myself with different weights. It is all the same. Your going to feel a pinch of any weight of BB. If you are feeling serious pain from Airsoft, tbh its not the sport for you. The only time I've felt excruciating pain is getting BB's in the ears and finger tips.

Hivemind187

[DM]-TheDOC- wrote: »

Also, if I'm not mistaken, semi auto would be used in "real" CQB scenarios ( CT units moving through occupied buildings) Thats open to correction though.

You are mistaken.

Semi and full auto have different uses at different times.

Semi is for precision shooting when you need to be absolutely certain of where your rounds go and what they are doing when they get there. You lose "stopping" effect though from using fewer rounds.

Full auto in cases where you are less concerned with what your rounds are doing means that in short controlled bursts you get tripple and quadruple taps on centre mass creating a much great potential "stopping" effect on the target.

In airsoft you tend to use short bursts of auto-fire because of the unfortunate tendency for airsoft rounds to go wild. You still use semi-auto for either precision shooting or for distracting fire (tapping the wall next to where an enemy is hiding to remind him to stay put).

Some folks are better with the semi-auto thing, particularly pistols in close quarters but if you have the option of full auto it makes more sense to confirm a hit by putting 5-6 rounds into an assault vest to let someone know they are hit than to risk 1 round bouncing off a mag pouch and being ignored right?

TheDoc

I know what you mean, in Wales I had an infuriating situation where i was hidden in a corner of a room popping people storming up stairs, but it was hitting places the player coudlnt feel and the noise going off they couldnt hear.

The only option left was using full auto ( this is where i infamously dispensed my 60 rounds that i fired all weekend) But I ended up ruining 3 lads from overkill.

I can normally always hear when a BB hits me so I dont see why anyone else should be different.

Like I said I don't have a huge problem against it, just think semi is more skillful. And its also an excuse for me to actually use my pistol, rather then my current situation where i just use it for laughs.

Dr_Pepper

The Unit only ever use single shot in cqc.

Hivemind187

Dr_Pepper wrote: »

The Unit only ever use single shot in cqc.

... And superman only ever uses eye-lasers!

kdouglas

OzCam wrote: »

I doubt it. The figures don't add up.

Even at the full 100m/s velocity, that's still only 1.25J. Since much human perception is logarithmic, a 20% increase is pretty insignificant. I would guess that the close range would have much more to do with it, since far less of the BB's energy is lost to atmospheric drag compared to a 20 to 30m engagement.

And, more importantly, cheap .12g BBS are likely to damage your gun, and that's if they feed at all.

PS: putting my safety officer's cap on for a second, the testing the chap did was valid, and pretty good, but the raw physics of the impact and the target's perception of the impact are two different things (as the tester noted). Since all airsoft guns in Ireland have to clock under 100m/s by law*, and since everyone should be wearing face protection in CQB anyway, I don't consider that the reduction from 1J to 0.6J is really worth the effort. Below a certain point, halving the hazard doesn't get you double the benefit. I'm willing to be convinced otherwise, but I don't see it.

Dex?

* let's not get into the nitpicky technical arguments, you know what I mean here.

Your calculations are wrong, there is no reduction in the energy, 1J gun is still 1J, regardless of what weight BB you put into it (minor exceptions for gas powered which I explained in an article on my blog)

By law, airsoft guns need to fire under 1 Joule, not 100m/s. 1 Joule just happens to be 100m/s with a 0.2g BB.

So while 100m/s with a 0.12g BB might be only 0.6J and 100m/s with a 0.2g BB is 1J, the comparison is incorrect since 1 Joule with a 0.12g BB is approx 130m/s


Further, if anyone is using 0.25g BBs or other weights, they should be very aware of this and ensure their AEG fires under 1 Joule, not 100m/s

liamo333

Dr_Pepper wrote: »

The Unit only ever use single shot in cqc.

Well that settles it!

TheDoc

I'm still pretty sure that semi auto is strictly used in closed environments. Then again perhaps I'm wrong....along with all the documentation on the web I just looked up. And from just pure common sense, it sounds more logical to use semi auto.

KD, update your blogs more, your an absolute databank for useful technological jargon regarding airsoft. I need more knowledge!!! And your last point is pretty important, I use .25 and my guns usually chrono in at around 24-260 and i get real worried, then Gerrout slaps the back of my head to remind me I'm using .25's.

And I would just completely disregard the slightest mention of m/s. FPS and Joules. As much as people, like oz, might freak out and say we "need" to use a different measurements.

But since feet epr second is the standard in most sites and retailers, and Joules is the mention in the law, why bother brining in a third, more confusing measurement. Play it to the masses, I'm sure most of the general airsoft populace could define what 1J equates to in FPS quicker then M/S.

Craigsy

[DM]-TheDOC- wrote: »

IAlso, if I'm not mistaken, semi auto would be used in "real" CQB scenarios ( CT units moving through occupied buildings) Thats open to correction though.

That would be the "Double-Tap", developed by the SAS

kdouglas

[DM]-TheDOC- wrote: »

The only time I've felt excruciating pain is getting BB's in the ears and finger tips.

Wouldn't call it excruciating, but on a cold day, yes they are quite sore spots to get hit

kdouglas

[DM]-TheDOC- wrote: »

I
KD, update your blogs more, your an absolute databank for useful technological jargon regarding airsoft. I need more knowledge!!! And your last point is pretty important, I use .25 and my guns usually chrono in at around 24-260 and i get real worried, then Gerrout slaps the back of my head to remind me I'm using .25's.

Thanks

I've been meaning to post more stuff for a while now, but it's been on the long finger...

As regards m/s, fps, joules etc...

Joules is the correct way of measuring it because you are taking into account not just the speed of the projectile but also the weight.

Metres per second is correct also (once you specify the corresponding weight) because the calculation to get the energy in Joules uses m/s not fps.

Feet per second is generally used because despite using the metric system for years now, alot of people still think in feet, it's also commonly found that alot of basic chrono's which measure just the speed will read in feet, not metres.

NakedDex

A rose by any other name...

One joule is one joule, no matter what weight the projectile given that one joule of energy is. Therefore, it is impossible for a projectile of higher or lower weight but with the same energy to impart more energy on it's target without outside influence (thereby imparting a higher kinetic energy on the target, causing more "pain").
It's fairly simple, in a closed system (ie without any outside influences other than the intended propulsion) a round of any weight, onto which 1J of energy is imparted, cannot gain or lose that 1J until the round reaches it's target. Upon reaching said target, the energy is changed from kinetic to heat, sound etc, as well as imparted energy upon the target and resultant kinetic energy from rebound from and/or deflection of the target. All of the expended energies in the impact will still add to one Joule.
In an open system (ie a typical operating environment such as a skirmish site), other factors must be brought into play such as friction, pressure, temperature etc. However, the majority of these have a negative impact on the energy of the round, decreasing it exponentially over time-in-flight. The two biggest are friction (of the air) and gravity.
To say a heavier bb could hurt more, implies that there is more energy in the heavier round than the lighter one, despite both having the same initial energy. At the point of expulsion from the barrel, both heavy and light rounds (in theory) have the same energy (disregarding energy lost during travel through the barrel). The difference simply lies in the speed of flight. A .12g round will have considerably less time-to-target than a .3g due to less work required to accelerate the lighter round (remember, energy is simply a measure of the ability to do work).

Since the energy is a constant due to the mechanical set up of the device, and the weight is predetermined by choice (and is thereby also a constant), the speed of the round must be the only variable.


Now, here's where it gets tricky.

At range, due to the outside influences, rounds in flight will begin to lose energy to the act of travelling (friction, heat etc). The question then becomes; "what is the energy of a .12g round fired at 1J in flight at 10/20/30ft compared to that of a .3g". Unfortunately, without a large-gate chronograph or a high-speed camera it's not that easy to tell as we don't know the speed the round is travelling to do the necessary math to determine the energy at those points. It's reasonable to assume there is one, albeit small and existing closer to the edge of the range of the round fired rather than within the first ten feet.

Busta Hyman

Hivemind187 wrote: »

The so-called "Full Auto ban" in CQB is not to prevent serious injury from fire. It is to curb the accidents caused by blind firing morons and cater to the needs of our more "sensitive" players (i.e. whingers who wear a t-shirt to CQB and then complain that "getting shot stings like the dickens!").

i went to the warehouse this weekend wearing my useual rigout that i use at HRTA which consists of a t shirt under my SAAV got hit a few times a bit stingy but ffs it aint like im missing an arm. but i will be wearing sleeves next w/e thats for sure.

desertstorm

thinking on naked dex's post i remembered reading about an alternative to a wide gate chrono in which you have two pieces of paper space 1M apart and then a microphones beside each page connected to a laptop with a simple sound recording program running, when the bb flies through the pages you look for the sound peaks&the time between them& hey presto then you've got m/s and the energy now in the bb!

A bit tedious but if you really wanted to find out it might be worth a shot if you had a bit of free time?

Also i cant say ive noticed a difference between weights,nor really cared i think it depends on where you get hit,that pain is relative, and its all part of the sport.

In saying that i still think overkill is something to avoid doing as a player as it seems like pretty bad sportsmanship,it can cause unwanted sorts of tension on a site if anyone knows what i mean

hrta

there is some noticed difference between weights of a projectile, i know this from reloading my own ammo, a heavier round will dump more energy in the target

extremetaz

desertstorm wrote: »

thinking on naked dex's post i remembered reading about an alternative to a wide gate chrono in which you have two pieces of paper space 1M apart and then a microphones beside each page connected to a laptop with a simple sound recording program running, when the bb flies through the pages you look for the sound peaks&the time between them& hey presto then you've got m/s and the energy now in the bb!

That would work and it's nowhere near as hard to set up as you might imagine - you just need the right software and a suitable recorder.

However, unless the paper is VERY light, it's going to take a significant chunk out of the energy of the projectile in the first instance - a second strike would probably stop it entirely if there was any sort of range between them.

Your idea though is still probably the most workable I've heard to date, it just needs one minor tweak - one mic on the AEG, one mic at the paper.

There will be a peak in the AEG sound profile when the piston stops at the end of its travel - for our purposes, this would be close enough to assume the start of flight of the projectile. From then it's a simple case of timing flight until impact with the paper. Varying the range to the target then will allow for the developement of a flight velocity profile.

It's a good idea 'storm - could work.

extremetaz

as for the "heavier hurt more" thing.

It will - it's physics. Has to do with momentum and the ability of a body to resist changes in velocity.

It's been hinted at by a few people so far, but vtec has it closest - it's all down to how easy it is to deflect the projectile.

This has nothing to do with the amount of energy in the round - but it's ability to resist changes in velocity. Lighter rounds require less energy to deflect than heavier ones. Furthermore, a projectile only departs energy on the target during deflection. Every action has an equal and opposite reaction, if they're pushing against you, you're pushing against them.

Once the round deflects, it is no longer pushing against you, hence energy transfer (and pain) ceases.

The heavier the projectile, the harder is it to deflect, therefore the more energy there is imparted during impact - hence, pain.

A very simple illustration is to watch what happens when rounds of various weight hit a *soft* target:
- lighter rounds will bounce way back
- medium rounds will bounce less
- heavy rounds will stop and drop

as long as the round is moving, it's got energy, therefore it hasn't imparted all it's energy to the target. Heavier rounds resist deflection better, therefore they impart more enery, bounce less, and hurt more.

hrta

i know this is airsoft, so dont get me wrong putting up terminal ballistics, but it is about projectiles.

Scalar Versus Vector:
An important difference is that momentum is a vector quantity - it has a direction in space, and momenta combine like forces do. Kinetic energy is a scalar quantity - it has no direction in space, and kinetic energies combine like "regular numbers".

You seldom see momentum mentioned, and when it is it is often misunderstood.
bullet physics nicely explains this, or the TKO value.

One can think of energy absorption (of a target) as Force x Distance, and momentum absorption as Force x Time. Hence, the heavier but slower bullet with the same energy will travel the same distance in the absorbing material, but because of larger momentum, will take a longer time doing it. It will therefore also impart a greater "kick" to the absorber object."

weeder

thought i might give some imput, personally ive noticed a .25 to hurt a bit more then a .20 on the field and leave me with a larger welt, obviously there are a number of factors to make this not a conclusive answer bt its in my own experience

Masada

Ive never had a welt from any airsoft hits, only a small mark sometimes., maybe it has more to do with the part of the body where your hit weeder, or even things like your skin/flesh etc.,.,

spicymchaggis

dunno, the only bb to break the skin on me was a shot from a psg-1 with a .28

Hivemind187

To expand on the subject of "pain".

The sensation of pain is dependent on a number of factors.

- Kinetic energy imparted (with specifics to BB's)
- The surface tension or ridigidity of the substance impacting the flesh (assuming bare skin hit).
- The location of the strike.

The energy aspect has already been covered so I'll briefly cover the other two.

Strikes impacting the flesh will give different intensities and kinds of pain depending on a number of factors.
- Subcutaneous fat content.
- Thickness of the skin.
- Distance of bone or cartilage below the flesh.
- Number of nerves in the impact area.
- Current levels of adrenaline and other chemicals in the brain which can "numb" the sensation of pain.

If, for example, a BB strikes an area like the knuckle the pain sensation will be strong for a moment as there is very little fleshy padding to protect the boney protrusion. However, there are also fewer pain nerves in that area and as such unless a strike were to causse damage to either the bone, the ligament, cartilage or the tissue the pain will not last long.

Alternatively, an impact to the skin in an area of high muscle density and tougher skin (such as the upper outer arm - tricep/deltoid region) will feel the impact slightly longer than the knuckle but its likely to be a far duller sensation due to the arrangement of nerves and tissues.

Someone who has been drinking a lot of caffiene and has been "in combat" for a while is likely to exhibit a greater propensity to ignore strikes simply because they cant feel them. the secretion of adrenaline and other chemical into the bloodstream has a peciluar effect o nthe brain. It somewhat switches off pain processing (temporarily) and has been known to allow people to continue operating even while horribly wounded. BB stikes by comparrisson wouldnt even register.

There is also the issue of gender. This is an evolutionary trait thats expressed better in males. During puberty male skin thickens and becomes less sensitive. The evolutionary advantage to this of course is that it makes hunting easier by allowing the individual to concentrate on prey rather than the various thorns and nicks in his hide. In females the same process does not take place (due to the presence of much less testosterone) with the skin remaining softer and more sensitive to environmental factors.

sliabh

extremetaz wrote: »

as for the "heavier hurt more" thing.

It will - it's physics. Has to do with momentum and the ability of a body to resist changes in velocity.

If you are right there, and it is momentum that is the thing deciding the level of pain, then the maths gets you get an answer.

Momentum = mass by velocity (p=mv for engineers).

So for a given speed, the heavier bb will dump more energy/hurt more on impact. But as we are restricted to a 1J energy limit the .25g BB will have a slower muzzle velocity too, and that will reduce the momentum.

Energy = 0.5 by mass by velocity squared.

And that is the crux. Energy is related to the SQUARE of the velocity, while momentum depends on the velocity on it's own.

So a 0.2g BB with 1 joule of energy will have a muzzle velocity of about 100m/s. And its momentum will be 0.02 Newton seconds (Ns).

A 0.25g BB with 1 joule of energy will have a muzzle velocity of about 89m/s. But its momentum would be 0.022 Ns or about 10% higher.

That said I challenge anyone to notice a 10% difference when hit!

If you are using a 0.12g BB the momentum figure comes out at 0.016 Ns. So there may be some sense to using the lighter ammunition.

Tigger

its a factr of impule which is dependants on time
of momentum
and of kenetic energy

extremetaz

sliabh wrote: »

So a 0.2g BB with 1 joule of energy will have a muzzle velocity of about 100m/s. And its momentum will be 0.02 Newton seconds (Ns).

A 0.25g BB with 1 joule of energy will have a muzzle velocity of about 89m/s. But its momentum would be 0.022 Ns or about 10% higher.

That said I challenge anyone to notice a 10% difference when hit!

i believe that the difference comes from the amount of energy that extra momentum allows the projectile to impart on the target.

it's important also to remember that we will be talking of small fractions of a Joule in the difference, so it's more important to consider the relative terms than abolute - and even to take a direct comparison, 10% additional impact energy is still significantly more.

Rhinocharge

Put simply, pain is only a state of mind.

sliabh

extremetaz wrote: »

i believe that the difference comes from the amount of energy that extra momentum allows the projectile to impart on the target.

Ah, but the energy is the same for each bb (1 joule) so no difference there :-)

extremetaz wrote: »

10% additional impact energy is still significantly more.

As OzCam pointed out, human perception is lograthmic. You need to increase the momentum by 2 or 3 times before most people will notice.

spicymchaggis

Rhinocharge wrote: »

Put simply, pain is only a state of mind.

well yeah, its the mind protecting the body so you dont go putting yer hand in a fire

Rhinocharge

spicymchaggis wrote: »

well yeah, its the mind protecting the body so you dont go putting yer hand in a fire

It's not the initial flame that burns you, it's the lenght of time it remains there. Even then the pain receptors may feel a tingle or a burning sensation. Only a fool would stick their hand into a flame.

Getting back to the BB question.

In my experience heavier bb's do hurt more. I'd rather get hit by a 0.12 then a 0.33. 0.12's bounce back, 0.33's don't.

Lemming

Rhinocharge wrote: »

Put simply, pain is only a state of mind.

Or .. if you're deviantly inclined, for jollies :pac:

OzCam

Pain is temporary.
Bones mend.
Women dig scars
And glory lasts forever.

TheDoc

""Someone who has been drinking a lot of

---

caffiene

---

and has been "in combat" for a while is likely to exhibit a greater propensity to ignore strikes simply because they cant feel them. the secretion of adrenaline and other chemical into the bloodstream has a peciluar effect o nthe brain. It somewhat switches off pain processing (temporarily) and has been known to allow people to continue operating even while horribly wounded. BB stikes by comparrisson wouldnt even register.""

I'm going to apologise to everyone....this segment snip from Hives always itneresting posts, has firmly instilled in me, that I'm a filthy dirty cheater

As someone who regularly goes through 4 cans of red "heart attack" bull a skirmish ( or the infamous 14 in wales) I have to say I still feel hits. Granted they don't hurt, and it makes me angry and I find solo holding an m16 rather easy, I still feel hits.

It would be pretty funny if I was actually a horrendous cheater and genuinely didnt know, and you guys just never said anything to me...I'm kinda spooked now

extremetaz

sliabh wrote: »

Ah, but the energy is the same for each bb (1 joule) so no difference there :-)

the energy is the same yes, but the momentum of the heavier projectile is greater (whilst the velocity is lower) - therefore it is harder to deflect and transfers more of that same amount of carried energy to the target - hence, you feel the impact more. :-)

MacAonghusa

Craigsy wrote: »

That would be the "Double-Tap", developed by the SAS

Credit actually goes to two British Police chiefs in Shanghai during the 1930s.

The double tap ("controlled pair" if you're a yank) is good for movies but in reality the SAS or anyone else will use whatever number of rounds it takes to stop a target. You don't take chances, you stop shooting when the target stops moving

Short bursts probably offer you the best balance of accuracy and stopping power.