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HPA is it over powered?


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first and for most this is not a flame/rant from me, i have no issues with anyone using it etc.

 

Here's the situation, there has been talk at a site i visit (semi only site), that HPA systems (polar star's) are unbalanced (vrs GBBR/AEG's), in so much that :-

 

- with a hair trigger fitted a person can spam shots as fast as there finger can move, faster then most GBBR/AEG's in full auto, which kinda defeats the semi only rule. (after seeing one in full auto (bb laser beam) i would hate to be on the receiving end of that)

- They seem to hurt a lot more then then AEG's (they have been chrono'ed etc and were below 350fps), yet i know 2 people who have have bled after being hit.

- the air tank on there back means they don't always feel there hits (its happened and the offender was warned etc)

 

From my perspective, after being on the receiving end from them, i have to agree with these points. But i was wondering what other people thoughts were on HPA rifles, are they over powered? do they seem to hit harder? is the tank a back shield?

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An HPA converted GBBR will not fire faster than an AEG, in fact have seen AEGs with dangerous rates of fire. A GBBR or a GBBR converted to HPA will be closer to real steel ROF. Polarstars however can have dangerous ROFs, think you need to be more specific. I personally am against high ROF guns no matter the power source, as you say they are OP.

With respect to bleeding from a HPA gun, I have bled from many an AEG too.

 

Our site chronos every gun at the start of the day on site supplied 0.2g BBs, if a site allows owners to use their own BBs however they are setting themselves up for people to be dishonest.

 

As far as the air tank meaning hits aren't felt.... I have to say the same about all the plate carriers, want them banned too?

While we are at it we should ban any gun that is better than the rental guns as it puts the rental guys at a disadvantage!

I get you are not having a pop intentionally but it is a poor argument IMO

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Our site chronos every gun at the start of the day on site supplied 0.2g BBs, if a site allows owners to use their own BBs however they are setting themselves up for people to be dishonest.

 

 

Whilst somewhat off topic people that are going to break the rules can do it regardless(i'd argue it's a deterrent but a small one for cheats). There are AEGs with quick change springs and GBBRs fitted with an NPAS can adjust the FPS at their discretion. Not to mention the talk of joule creep in the GBBR thread. I used to have a mag set aside as a chrono mag but the only site i've seen even try and enforce using 0.2s for chrono was the sandpit and they did it by saying we have mags to use, which not only meant you basically needed a gun that took common 5.56 STANAGs but if you opted out it wasn't questioned.

 

As far as drawing blood goes i've had AEGs do it on bare skin at about 15 metres and I would hazard a guess sniper rifles can do it at a greater range. Especially on bare skin. Outside of that the only time i've had medium range shots(15-30 metres) draw blood was when players failed chrono and then seemed to be using very familiar guns...

 

I could see HPA setups causing a problem in the specific semi only setting you mention sp00n. However I've played against people using them in games using run of the mill skirmish rules and never had an issue.

 

As far as hit taking goes with a tank on. That sounds a bit dubious; A BB hitting any material on your person should at least be audible, after all plate carriers have no give and don't cause problems with hit taking. I accept it may happen on the rare occasion but outside of that it seems a bit suspicious, e.g. getting 5 reports of non hit taking in a day.

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An HPA converted GBBR will not fire faster than an AEG, in fact have seen AEGs with dangerous rates of fire. A GBBR or a GBBR converted to HPA will be closer to real steel ROF. Polarstars however can have dangerous ROFs, think you need to be more specific. I personally am against high ROF guns no matter the power source, as you say they are OP.

 

With respect to bleeding from a HPA gun, I have bled from many an AEG too.

 

Our site chronos every gun at the start of the day on site supplied 0.2g BBs, if a site allows owners to use their own BBs however they are setting themselves up for people to be dishonest.

 

As far as the air tank meaning hits aren't felt.... I have to say the same about all the plate carriers, want them banned too?

 

While we are at it we should ban any gun that is better than the rental guns as it puts the rental guys at a disadvantage!

 

I get you are not having a pop intentionally but it is a poor argument IMO

 

 

i have updated my original post,

 

-the issue i believe is with polar star's

 

-its a fair point, but it dose seem to be an issue with the 4 HPA guy's more than any one else.

 

-This too is a fair point about site bb's etc

 

-i never said to ban any thing ... but yeah this too happens to plate carriers

 

-i never said to ban anything ... i mearly stated that i did agree with there points ... I NEVER SAID TO BAN ANYTHING :lol::lol::lol:;) to be honest if anything i think they may be asked to "tone down" there ROF

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I now have 7 mates with Polarstars and when we're all running on the same team I don't feel that our chances of winning are any greater. I don't think they hurt more or cause more damage, it's just how they're set up.

I think it's important to differentiate "HPA" and things like Polarstars and SMPs though, because HPA'd GBBRs are still a massive handicap over AEGs, unless they're using a casket mag or something. In fact you could even argue that HPA'd GBBRs are more of a handicap than standard ones because the reloads take longer due to the hose swap.

You could still truthfully refer to them as "HPA" guns though.

Polarstars and SMPs can be tuned to give the greatest performance possible from an airsoft gun for a lot less than it'd cost to do with an AEG, and more reliably, and in a more versatile system... But you need to know how. And a lot of people don't.

A properly tuned Polarstar will rape the face off an upgraded AEG, hands down every time, they can't be beaten on consistency, it's just not possible. But the gun doesn't make the player.

So long as site limits are met, I have no problem with them at all. As a GBBR user I feel that every gun I go up against has a significant advantage over me anyway, whether it be a standard AEG, an upgraded one, or a HPA P* or anything... Well, short of a sniper. So perhaps it's just my mindset because I choose to handicap myself on purpose.

I think they probably should have set ROF limits though, because they're capable of 60+ rps and my site limit is 370... Many owies. Don't be a cock with the restrictions though, I'd say to set it at around 30. I'd argue that's getting close to being "too high" but it's what I'd aim for if I was building an AEG, and not for the auto ROF, but for the trigger response.

Also since they're powered by compressed air, and the volume of it can be altered, and most people have no idea what any of that means... Joule creep becomes a factor.

Especially when sites (dangerously) insist on chronoing everyone on a .2g bb. Guns should be chrono'd using the weight the player intends to use, because when guns have a barrel volume of less than what the gun fires down the barrel, adding heavier ammo increases the power. It doesn't stay level due to the fps drop acting as a counter balance. The fps drops by less than it should due to the way power is applied, and the joule output increases. It's especially dangerous in GBBRs, but also HPA rifles, spring snipers and to a lesser extent, long barrelled AEGs.

So that might be why you feel like they hit harder, 'cos if they're set up with the poppet dwell on the longest setting and they hit the limit on .20s, when they add heavier weights to play with, they're actually going to be sending their muzzle energy, their joules, over the equivalent limit of .20s.

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Ed, is there anyway to check for joule creep ? would chrono'ing say 1m after the barrel prove this?

 

(please note i have no say in this site, rules or other, i just play there)

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Muzzle energy is muzzle energy, full stop. The very instant the BB leaves the barrel it begins slowing down (same with real bullets) as there's nothing propelling it anymore. If a polarstar/wolverine/whatever gun chronos at 328fps then the BB is travelling at 328fps, exactly the same as an AEG in that respect.

 

Are they inherently 'OP'? No, I can spam the trigger on my TM as fast as my finger can move (pretty fast, few times I've had 'semi only!' shouted at me), same as any well set up gun... can you crank them up to be outrageous 50RPS BB hoses, yes, and if a player does then it's them that's the problem not the gun they're holding!

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Ed, is there anyway to check for joule creep ? would chrono'ing say 1m after the barrel prove this?

 

(please note i have no say in this site, rules or other, i just play there)

If I had a chrono I'd make a video and demonstrate it.

 

The best example I can give is with my gas L85. I once set it up for 370fps with .20s which is my site limit, and then I decided to chrono it again using .28s just to gauge the amount by which the fps would go down.

 

I got the same reading... 370fps on .20s = 370fps on .28s.

 

On .20s the joule output of 370fps is, according to this forum's app, 1.27J

 

The app also says that if you chrono at 370fps on a .2, and then try with a .28, you ought to get 312.7fps BUT that's because the equation assumes the same amount of power will be applied to both shots, but it isn't. The heavier shot stays in the barrel for longer because it takes more energy to get it going, and because it's there for longer more energy gets applied.

 

So because of this, and because gas rifles fire so much more gas than they need to down the barrel, I was effectively 67.3fps over the limit, and 370fps on .28s equates to 1.78J

 

So I went from 1.27L to 1.78J with nothing but an ammo change.

 

And there are sites that insist people chrono on a .2

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I also wonder whether some of the issue is ammo weight. We very rarely get shot at 0 metres, generally we get shot at 10 metres at least. The heavier the ammo the more energy it maintains as it travels, it isn't slowed as much by the air. So while (in theory as ed as shown not in practice due to joule creep) the BB velocity is initially lower the speed is maintained for further. Those with upgraded guns are probably also running heavier weight BBs as they have larger hop patches and have tuned their gun and it can now shoot nice and far and more accurately with heavier weight BBs which are deflected less over distance.

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I also wonder whether some of the issue is ammo weight. We very rarely get shot at 0 metres, generally we get shot at 10 metres at least. The heavier the ammo the more energy it maintains as it travels, it isn't slowed as much by the air. So while (in theory as ed as shown not in practice due to joule creep) the BB velocity is initially lower the speed is maintained for further. Those with upgraded guns are probably also running heavier weight BBs as they have larger hop patches and have tuned their gun and it can now shoot nice and far and more accurately with heavier weight BBs which are deflected less over distance.

Yeah, that's another factor.

 

Whilst a gun using .2s and .25s might both be hitting the same muzzle energy at the muzzle, 25m down range the .2 has bled off most of what it had, whereas the .25 still has more.

 

They'll also weirdly arrive at around the same time, because although the .2 sets off faster, it also slows down faster, whereas the heavier shot maintains a lower velocity for a longer period of time.

 

So obviously the heavier you go with the weight, the bigger the energy transfer to the target, whether they're being dangerous with joule creep or not.

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I've never seen any Polar Star stuff for sale in UK, does everyone have to import from US?

 

EDIT - Never mind, found The Grange sell em.

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So obviously the heavier you go with the weight, the bigger the energy transfer to the target, whether they're being dangerous with joule creep or not.

 

Once you combine the two I think you get to the bottom of why the HPAs are very accurate and hit much harder than they should. Heavy BBs, joule creep combined is more energy and more accuracy and more speed maintained. The recipe is dangerous if the user is specifically exploiting it, even at range they could be hitting above the magic 1.1j limit. Combine that with a ROF that is just insane and yeah I am glad I don't see them very often.

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I've been hit by them a few times even at about 150m away and they sting like a biatch, especially on tender areas like the head and neck when uncovered

 

I always take a mesh mask but mainly use it when hpa rifles are around

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The trajectory project does have a calculator for Minimum engagement range, and given a power level different weight BBs do have different MERs. Given 2.32 Joules (500fps 0.20g). 0.20g is 12 metres but 0.43g is 23 metres.

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I've been hit by them a few times even at about 150m away and they sting like a biatch, especially on tender areas like the head and neck when uncovered

 

I always take a mesh mask but mainly use it when hpa rifles are around

150m sounds a little... bullshitty lol. I think 100m is about the absolute extent of airsoft range that can be useable tbh, 'cos once you lose sight of the shot to walk it onto the target, it could be doing anything, especially as the energy bleeds off.

 

The longest range shot I've ever seen was 107 yards by a HPA bolt action sniper firing at 550fps and even then it couldn't be done consistently - there's a video of it:

 

Here's a video my mate made using his P* DMR as well, I think he was hitting around 80m:

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I'm guessing 150ft not m!

 

There's a couple dif guys who often turn up at The Mall with a Polastar, and generally someone will complain about getting a line of 50rps dots down their arm. I've been peppererd few times by them and seems to hurt/sting no more than any other gun at close range.

 

Perhaps the additional air being used in these helps the BB keep it's force better over long ranges? Has anyone compared the difference in BB spin between CPA and AEG? would take lab conditions to do that properly, but has anyone tried testing whether hop-up amount creates the same or differing amount of spin between AEG & CPA, as the hop-up should act as an amplifier of spin applied by the raw air, and hopefully create a noticeable difference in when hop-up amount started making the BB arc upwards.

 

I wish someone university or similar would actually work out the balance between the various conflicting laws of physics applicable to airsoft so answering these kind of questions didn't seem like a cross between alchemy and voodoo.

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I wish someone university or similar would actually work out the balance between the various conflicting laws of physics applicable to airsoft so answering these kind of questions didn't seem like a cross between alchemy and voodoo.

 

The laws of physics don't conflict. That kind of the point. It's people understanding (or indeed lack thereof) and a lack of proper demonstration of the variables that leads to confusion.

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150m sounds a little... bullshitty lol. I think 100m is about the absolute extent of airsoft range that can be useable tbh, 'cos once you lose sight of the shot to walk it onto the target, it could be doing anything, especially as the energy bleeds off.

 

 

Here's a video my mate made using his P* DMR as well, I think he was hitting around 80m:

 

your mates vid was pretty good, have subscribed to his channel :-)

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The laws of physics don't conflict. That kind of the point. It's people understanding (or indeed lack thereof) and a lack of proper demonstration of the variables that leads to confusion.

 

Indeed conflicting is a poor choice of word, the conflict is only in the opinions of people citing different ones as having the greater effect. What i mean is the ratio of the various laws that can be deemed to have an effect.

 

I've a couple friends who work as supply teachers, both with enough Physics knowledge to teach the subject. They gave up trying to argue/define the full effects of inner barrel bore/length & hop-up after i posed the question, if there'd been less beer and smoke in the room I might be able to recount the two laws/prinicpals they were arguing would have the greater effect.

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The principles at work aren't complicated, it's how they all work together and the sheer number of variables that make it an uncertain thing.

Hop is just a brake that only acts on one side of the BB. More hop = more brake, so the bottom of the BB goes faster relative to the top, so you get more spin.

Then obviously more spin causes shots to go up, less causes them to go down. That's the work of the Magnus effect.

Heavier BBs can be spun faster without it causing them to climb upwards because of their weight, so they maintain their spin longer, as well as their velocity due to it taking more air resistance to slow them down, and so they reach out further, and carry their energy better.

The one thing that I REALLY want to get my hands dirty and test properly, is whether or not widebores are actually better for accuracy at range. Because in my head, that entire concept makes absolutely no sense whatsoever.

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The principles at work aren't complicated, it's how they all work together and the sheer number of variables that make it an uncertain thing.

 

Yeah and that's the stalemate of being unable to determine this precisely without a lab my friends got to.

 

It all got abit hard fow me to follow, but they gave me enough school-kid summary to gather the following in relation to barrel bore, please forgive me if my memory has failed and i get anything jumbled or miss any key relational points;

 

They said that the spin of the BB would create a layer of pressure/air around it, and that this can reduce the effects of the surrounding air/environment on the bb as its deflected by it. They said there's an optimum for spin (depending on the size/mass of the BB and force applied) and too much spin/instability can create an effect 'i forget the name' where this pocket of air/pressure around the object isn't stable, and vents pressure/air in one direction, pushing the object away in the opposite direction.

 

They agreed that the stability of this pocket of air/pressure around the BB is the main factor in accuracy. That relational to amount of spin applied by the collision with the hop-up, there would be an optimum bore for a barrel that would allow this layer of vacum/air to form better, and that there was another optimum in terms of this pocket itself that would reduce the amount it is effected the moment it leaves the barrel.

 

They said that assuming the BB was always the same dimensions/mass, that these 'optimums' would differ depending on the volume of air being used to push the BB and the force/speed it travells at, the volume of the barrel, the temperature and the amount of air-pressure at the beginning and end of the barrel.

 

They seemed to think this would be very easy to calculate in a lab and considering that theres only about a dozen diff barrel lengths commonly used they were suprised no-one had done so already. They said therefore there's no universal principal of one barrel bore being 'better' or 'worse' for accuracy, but it'd be easy to define a vague optimum (they consider the increments of availible barrel bores being 0.01mm very vague when using a 6mm projectile) for different combinations of cylinder and barrel volume, that that a precise amount of hop-up to set could then be calculated.

 

They said for HPA or gas, it'd be much harder to define as they doubt the volume of spread of pressure in the air/gas released for each shot is anywhere near consistent enough, and went as far to say it might be too inconsitent for the bore to make a tangeable difference in this manner. They also said it's possible that an AEG could have a similar amount of inconsistency due to build quality to also make it largely irrelevant, that the amount of consistency required for the bore to matter to accuracy at all could end up being something of an aerospace/F1 build standard that isn't seen in airsoft at all.

 

TLDR: It's possible to calculate exact optimum bore, but differs depending on cyclinder/air volume/force applied and initial unadjusted barrel volume (assuming 6mm for 6mm projectile). That it's also likely these are inconsistent enough due to build-quality of airsoft guns not being aerospace/F1 standard for barrel bore to make no tangeable positive or negative difference. (unless an extreme like 6.5mm or 6.00000000001mm for 6mm projectile etc)

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They said for HPA or gas, it'd be much harder to define as they doubt the volume of air/gas released for each shot is anywhere near consistent enough, and went as far to say it might be too inconsitent for the bore to make a tangeable difference in this manner.

HPA is exceptionally consistent, that's why people are moving over to it. It allows you to apply more air than could fit in a cylinder, and it allows it to be more precisely applied than it can be from a cylinder by a piston.

 

Though gas is by its nature ridiculously inconsistent as it is temperature dependent, and using it lowers its temperature. The only reason gas rifles have anything like consistent shot placement is because they fire so much more gas down the barrel than they actually need to, that a shot has ample to use what it needs, so the shot weight creates it's own consistency in a way, by just making use of an effectively endless supply. If that makes sense?

 

Of the volume of gas sent down the barrel, a .2 probably only uses about 20% of it, if that. The fact that there's still 80% helps with the consistency because how much gas gets applied to the shot depends more or less solely on its weight.

 

Heavier shots will simply use a higher percentage of the gas supplied down the barrel.

 

You'd probably need the barrel to be 2m long, or to use BBs weighing in excess of 1g before you got to the point where the gas supply fell short of the barrel volume.

 

But yeah, back to the whole "cushion of air" thing. I just don't buy it. It's like heaven... It sounds nice, but frankly, it's too good to be true. So by the same token, I'll believe it when I see it, and not before.

 

If a barrel is wider, the BB can more easily ricochet down it instead of flying straight, because there's more space for it to bounce around.

If a barrel is narrower, then it'll get sent straighter.

 

That just makes more sense to me, and based on the fact that tightbores are more accurate than not-tightbores, it just stands to reason that it's true.

 

So how can a barrel that's wider than a standard one be more accurate? There is just no logic there that I can see at all.

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If a barrel is wider, the BB can more easily ricochet down it instead of flying straight, because there's more space for it to bounce around.

If a barrel is narrower, then it'll get sent straighter.

To be fair in the same breadth you could say a thinner one means more bounces in a quicker space of time. I think with several inner barrel manufacturers making wider barrels there has to be something in it. Why bother if not? Add to that the large amount of people switching to orga barrels and others and having good results there's clearly some benefit.

It's likely both achieve a similar outcome through different means if anything, neither is likely to be hugely worse or else so many people wouldn't use them.

 

With simple logic tighter is better but i dont understand why you can't believe in the air cushion proposal, it's more than plausible, it's not like a bb holds much mass . just depends which theory you subscribe to but I highly doubt people who've spent significant amounts of money on high end stuff like ptws and p*'s run wide bores over others for no reason.

 

 

Or it could all make no difference and it's literally just the quality of the components that make the difference :lol:

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