Barrel length

[DanBow]

Does barrel length make a difference in airsoft? Will an M4 shoot the same distance as, something like, an MP5?

 

[JimFromHorsham]

A well set up short barrel will outshoot a poorly set up long barrel .

too many variables to just say yes or no I’m afraid . 

 

[Adolf Hamster]

Outside of the extremes, not really.

Or at least it's generally hard enough to get a gun dialled in well enough to where the nominal barrel length is something to care about.

So no need to stick a longer barrel in, if anything doing so will change the voluming requirements so unless the cylinder volume is changed to match the new length a longer barrel is as likely to make the gun shoot worse.

 

[Impulse]

In AEGs it's way too complicated for a simple yes or no. Cylinder to barrel ratio is what affects AEGs, but honestly it's pretty minor. In gas guns, barrel length affects how it performs because of joule creep, so when using heavy BBs, a longer barrel gun will typically shoot harder than a shorter barreled gun, though this isn't necessarily a good thing as it can bring guns over the limit. As someone who likes both gas guns and long-barreled rifles, it's something I'm constantly struggling with  

 

[Leo Greer]

I'll second the above posts, as well as add this: In general, a very short barrel can be made to shoot just about as well as a long barrel. Airsoft does not benefit in any way shape or form from a long barrel, as the only thing the BB needs is enough time to fully stabilize in the barrel. In RS shooting barrel length is much more important because RS bullets travel faster and have much less time to stabilize. How fast BBs stabilize in your RIF is individual to your setup, your BBs used, and several other factors.

As a general rule... 300mm seems to be the sweet spot where accuracy and length meet. You gain nothing by going above, but may gain accuracy by lengthening to 300mm. However, for example, my primary uses a 260mm and gets amazing accuracy. This is just a ballpark and not a hard rule.

Range in general is governed by the joule output, BB stability, and BB backspin/weight. These are all, for the most part, independent of barrel length.

 

[Pseudotectonic]

A longer barrel will shoot more fps than a short barrel with everything else the same because the BB has more runway to accelerate

Heavier BB requires less runway to fully accelerate hence there is this thing called joule creep where it shoots more joules when switching to a heavier BB

 

[Adolf Hamster]

A longer barrel will shoot more fps than a short barrel with everything else the same because the BB has more runway to accelerate

Heavier BB requires less runway to fully accelerate hence there is this thing called joule creep where it shoots more joules when switching to a heavier BB

This is the case for gas and hpa guns, but not really so much in aeg's

 

[Pseudotectonic]

This is the case for gas and hpa guns, but not really so much in aeg's

Why? How?

 

[SSPKali]

Why? How?

AEGs have a set volume of air in the cylinder they will force down the barrel.
 

Gas guns (and I think HPA too. I don’t own one so no first hand experience) will keep pushing out gas to fill the volume behind the BB until it leaves the barrel and the pressure drops allowing the rocket valve to close and divert the pressure to cycle the action.

TM gas rifles have 250mm barrels no matter the outer barrel length to limit Joule creep and keep within Japanese laws.

 

[Cannonfodder]

For aegs it's down to the ratio of the cylinder volume to the inner barrel volume. If the volume of the barrel is greater than the cylinder the air will stop pushing on the bb before leaving the barrel.  Conversely too short (lower volume) and the bb will have left the barrel before the air can fully expand.

In a gas gun the gas carries on pushing the bb as it expands so (assuming every other variable is matched) a longer barrel will give more time for the gas to push the bb and so give it a higher muzzle energy 

 

[Adolf Hamster]

Why? How?

It's to do with an aeg being a fixed energy system whereas a gbb/hpa is a fixed pressure system.

If you make the bb stay in the barrel longer (wether it be a longer barrel or a heavier round being slower to accellerate) then the gas gun/hpa is just going to keep adding more pressurised air until the bb leaves.

Whereas with an aeg it can't have more energy than was stored in the spring to begin with.

That's a bit of an oversimplification as there's all sorts of gas expansion shenanigans going on and there's the whole thing with weighted pistons but its close enough for government work.

 

[Pseudotectonic]

But surely joule creep also happens with AEG?

 

[Leo Greer]

But surely joule creep also happens with AEG?

Of course. Gas supply is just severely more limited with AEGs. It's not even close. Even on .20g BBs, you start running out of volume at 509mm with an efficient AEG. You could make the barrel of most GBBRS four feet long and still have tons of extra volume.

 

[DanBow]

About as clear as mud but I think I understand. lol

 

[Pseudotectonic]

Say you have a gun, with a 400mm barrel, and you chop it into a 200mm barrel or 100mm barrel or 30mm or 10mm barrel, you will see an FPS drop (probably not linearly), therefore you will have a little less range from that lower FPS, until eventually you reach 0.1mm barrel where the BB would have lost so much FPS it will have little speed and just drop to the floor in front of you within a few meters and it will have lost so much accuracy it will be dropping left and right in front of you in a rather large spread pattern

 

[Cannonfodder]

you will have a little less range from that lower FPS,

Higher fps does not equal longer range, if this was the case then nobody would buy TM guns

 

[Pseudotectonic]

But slower FPS equal shorter range, if FPS doesn't affect range then pistols would be shooting the same as a sniper

 

[Adolf Hamster]

But surely joule creep also happens with AEG?

On paper yes, but nowhere near as impactful as you'll get from the gas powered stuff, enough to where it's drowned out by all the other shenanigans going on.

You can get more significant creep by weighting the piston which the bolt actions can exhibit, but that's counterproductive to the aims of most aeg users when it comes to avoiding pme in auto fire.

Higher fps does not equal longer range, if this was the case then nobody would buy TM guns

All other things being equal, more energy does mean more range.

The reason tm's seem to buck this trend is because some guns are built more equal than others.

It's worth noting that the whole "fps doesnt matter with a tm argument" always seems to fall flat on its face when the gun in question is a vsr.

That said, the general point that raw fps alone making for more range is not the same as effective range, which is what you're going to percieve as i aimed, i fired, the hit landed, the target felt it.

 

[Sewdhull]

It's going depend on your cylinder volume what the max barrel length should be, along with BB weight.

Whilst FPS matters for range you lose FPS very quickly once the BB has left the barrel.

The main things are energy, which is a combination of speed and mass, and the BB spin.

A heavier BB will go further than a lighter one at the same energy, but a heavier BB needs more time to pick up the energy which can only be done with more push in the barrel or more barrel to get pushed in.

Aegs have a fixed cylinder volume so your spring will increase the pressure but not the volume as it gets stronger.

More pressure is faster acceleration so you can run out of barell with plenty of air pressure still in the barrel.

Heavier bbs need more pressure to accelerate them so they accelerate slower and spend more time in the barrel and pick up more energy by the time they leave the barrel if it's long enough.

But for range it is the bbs spin that creates lift whilst moving forward and extending the range and heavier bbs slow down slower than light ones extending range still further.

There isn't a lot of science in Airsoft but the Airsoft trajectory project from many years ago did some.

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

Since an aeg is looking at 1.14 joules here in the UK, things like air seal and hop matter more since that level of energy is easy to reach even with 300mm barrels, or shorter.

FPS matters less than the joules.

 

[gavinkempsell]

Don't listen to their 'informed' gobbledegook... size doesn't matter, I've been told that many times from many people i know intimately.