Relationship between fps and range

[Beethoven]

informed airsofters might find this a silly question to ask. i was told that, for example, the scorpion evo has a potential range of 70 metres. However, another gun, with a similar fps of around 320 fps has a range of approximately 50 metres. I had assumed that the higher the fps, the longer the range. Why is this not so?

[BrightCandle]

One of those ranges isn't right. Given equal FPS and both having working hop units they will achieve the same range. There isn't anything magically in an airsoft gun its pure physics.

[Beethoven]

One of those ranges isn't right. Given equal FPS and both having working hop units they will achieve the same range. There isn't anything magically in an airsoft gun its pure physics.

I thought so. The question has been bugging me all night. Either the guy who told me this was talking bs or maybe I misunderstood him. If the scorpion could reach 70 metres, it must be with a different spring in it.

 

Sorry for the silly question.

 

Ps, I have a Physics 'O' level, but that was years ago. I never really understood the subject anyway.

[ImTriggerHappy]

Scorpion evo does not have an accurate range of 70 meters thats bullsh*t.

You can get range differences though with guns that are similar fps.

Range is as much about stability as power.

The air travelling through a bb gun travels much faster than the bb so just power alone isn't enough. You need stability which is mainly down to hop bucking, nub, barrel quality and a little bit about the hop unit itself.

If you can get good airseals and use a lower powered spring you can get a less violent push of air that will equate to the same fps but with less turbulence exerted on the bb which gives a much more stable flight.

 

BrightCandle is right you can't change the physics but there are lots of different forces working that have an effect not just one.

 

A slower longer push gives a more stable flight than a quick shove.

 

Edit; Even with a bigger spring it wont do 70 meters. Drop a grands worth of custom made parts in it and you might get a good range but still definitely nowhere near 70mtrs.

[Beethoven]

Scorpion evo does not have an accurate range of 70 meters thats bullsh*t.

You can get range differences though with guns that are similar fps.

Range is as much about stability as power.

The air travelling through a bb gun travels much faster than the bb so just power alone isn't enough. You need stability which is mainly down to hop bucking, nub, barrel quality and a little bit about the hop unit itself.

If you can get good airseals and use a lower powered spring you can get a less violent push of air that will equate to the same fps but with less turbulence exerted on the bb which gives a much more stable flight.

BrightCandle is right you can't change the physics but there are lots of different forces working that have an effect not just one.

A slower longer push gives a more stable flight than a quick shove.

Edit; Even with a bigger spring it wont do 70 meters. Drop a grands worth of custom made parts in it and you might get a good range but still definitely nowhere near 70mtrs.

Thanks for the info. The guy who spoke to me about the range was praising the merits of the scorpion, with a view to selling me one. What do you think of the scorpion?

[ImTriggerHappy]

Thanks for the info. The guy who spoke to me about the range was praising the merits of the scorpion, with a view to selling me one. What do you think of the scorpion?

Its one of the best guns on the market.

[Beethoven]

Its one of the best guns on the market.

Thanks trigger, much appreciated. Its £300 though, but as with everything else I suppose you have to pay for quality.

[ImTriggerHappy]

Thanks trigger, much appreciated. Its £300 though, but as with everything else I suppose you have to pay for quality.

Where are you buying from?

[callumbagshaw]

Thanks trigger, much appreciated. Its £300 though, but as with everything else I suppose you have to pay for quality.

 

I've heard really good things about the evo, and I've seen the ASG bren in action (which i believe is the same line, so probably similar internals & results, but it's a bigger rifle), so a +1 for them from me.

 

At that price bracket though, if you prefer the more traditional M4 look, you'll get similar performance with Krytac SPR & CRB, and the ASG 'devil' range looks pretty serious too.

[ImTriggerHappy]

 

I've heard really good things about the evo, and I've seen the ASG bren in action (which i believe is the same line, so probably similar internals & results, but it's a bigger rifle), so a +1 for them from me.

 

At that price bracket though, if you prefer the more traditional M4 look, you'll get similar performance with Krytac SPR & CRB, and the ASG 'devil' range looks pretty serious too.

Nope the bren and evo are very different.

 

The krytac is a totally different animal to the evo. The krytac is heavier but has fractionally better range.

 

The evo has faster trigger response, higher rof, 3rnd burst and built in battery protection for using lipos.

 

Build quality is about the same and so is accuracy.

 

Both are good but the user experience is very different.

[Samurai]

70m is easily achievable. 70m where you can actually hit a target is very hard to achieve with sub 350 fps. So it depends what range he was talking about. Max range is way over 70m but you have to aim 30-40 degrees up. Of course that's silly and says nothing about the gun.

 

A range where you can most of the time hit a human sized target is about 50-60m with normal AEGs.

[ImTriggerHappy]

70m is easily achievable. 70m where you can actually hit a target is very hard to achieve with sub 350 fps. So it depends what range he was talking about. Max range is way over 70m but you have to aim 30-40 degrees up. Of course that's silly and says nothing about the gun.

 

A range where you can most of the time hit a human sized target is about 50-60m with normal AEGs.

Thats wy I said accurate range.

 

I would say that most stock aegs struggle for any reliable accuracy at 50 mtrs.

For a gun to be accurate I would expect to be able to hit an a4 piece of paper 8/9 in 10. At 50 metres the best I have found stock is the Real Sword type97, Krytac Crb and G&P war rifle.

[Airsoft-Ed]

Range is dictated by BB weight, hop and power - that's joules rather than fps.

BBs are generally the most stable flying between 280 and 320fps, this isn't something I can prove, it's just something I've noticed through experience (I've been playing around 7 years).

So to get the most out of your gun, you want to be using the heaviest ammo you can that will give you an fps reading in that bracket, whilst still being light enough for your hop to actually send it flying level, of course.

Why heavy ammo? The added weight makes it less susceptible to air resistance, it might start off slower than a lighter bb but it'll maintain its speed for a longer period of time. To the point where beyond a certain range it will actually be travelling faster than the lighter bb that set off going faster, just because the lighter faster shot will decelerate at a higher rate.

The other thing about heavier ammo, is that it retains the spin applied by hop for longer, making it actually maintain it's lift for longer. So even though it's heavier and you'd expect it to be more prone to the effects of gravity, that's actually not the case because it spins for longer and actually fights gravity for longer.

How does that make any sense? Well the hop rubber is basically a brake, right? It's a brake applied to only the top side of the BB, the more hop you apply the more harshly that one side of the BB is slowed down, thus the greater the spin - we all know how hop works.

But for a heavier shot, more hop is required to maintain the same - level - flight, so it gets more spin added, and that's precisely why it maintains the spin longer, because it's spinning faster in the first place.

So when people say fps doesn't give more range, they're not necessarily wrong, but it'd help if they clarified by saying that JUST more fps doesn't give more range. If you just stick a bigger spring into a gun and run the same ammo through it, the shot won't fly with much stability, the air resistance will just slow the shot down faster, and you'll probably end up with so little extra range that it just won't have been worth it. Especially once you consider the negative effects of adding a heavier spring will have had on the gearbox - more stress on the gears, the motor, your trigger response and rate of fire are going to suffer, and for what?

But, if you up the power via the spring, and then also increase the weight of the BB - ideally to drop the fps back down to what you were shooting at before with the lighter weight, you will hands down, 100% of the time see a range increase.

The thing that people get hung up on, is that they don't understand why you'd increase the fps only to decrease it again with heavier ammo. They feel like they've taken a step forward only to take the same step back, but it's not the case because bb weight is everything.

A .2 travelling 300fps will not travel as far as a .25 travelling the same speed. So a .46 travelling 300fps? Range for days.

Why'd you think sniper's use heavy ammo? It's all physics.

[callumbagshaw]

Excellent post ed!