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Would this work re: extended cosmetic barrels

would venting a wider barrel help alleviate back pressure?

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#1 spacephrawg

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Posted 19 October 2011 - 10:31 AM

So we all know that a longer barrel creates more drag on the dart, slowing it down, unless you're using a pump system. And we know that if you have a wider barrel on there for cosmetic purposes, it better be a bit wider or else you'll have a problem with back pressure. However what if I don't like the look of a fat barrel that suggests either that it's supposed to be a suppressor, or conversely that it comes from the Warhammer universe? What if the barrel i want to put on there is only a mm or so wider than the stock one? There would be a back pressure problem, right?

Welllll, what if you put in spaced vents in that slightly wider barrel? say that barrel extension is inside the the outer shell of the recon's barrel extension piece. The vents could be easily hidden, right?

Would this work? I'd like to get your opinions before I try it.

Related: I've got an Alpha Trooper and it gets great range stock. I preordered the upgrade kits from Orange Mod Works for it and they claim it would give it a 50ft range or so. Sounds great but what if i were to try cutting the internal barrel down and putting in a wider one that comes out the end of the gun? Less narrow barrel = more range, right? I can't see why this wouldn't work in theory but again I'd like to run this by the experts, i.e. you guys, before i try it.

Thanks in advance.
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#2 taerKitty

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Posted 19 October 2011 - 10:35 AM

'Round here, you try it, then tell us. Try another NIC site if you want to actually play 'Ask the Guru'.
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#3 Langley

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Posted 19 October 2011 - 11:10 AM

So we all know that a longer barrel creates more drag on the dart, slowing it down.


Ordinarily, it is more or less against the rules to post asking for advise before you try something. But in this case, your assumptions about physics are pretty far off, and I want to take the opportunity to help everyone understand this, because it is a common misconception among new and younger nerfers.

LONGER BARREL = GREATER VELOCITY (to a point)
GREATER VELOCITY = BETTER RANGE (universally)

The third paragraph of This Article explains it pretty well. To try and explain it in basic terms, consider this: once a dart leaves the barrel, it stops accelerating and starts slowing down due to air friction (drag). If there is enough air pressure in the barrel for a net positive force on the dart, the dart is accelerating while it is in the barrel. So if you can maintain that air pressure, and make the barrel longer, the dart will have more time to accelerate (increase speed) before it leaves the barrel, and will leave the barrel with a greater velocity.

Now there is a point where, as the dart moves down the barrel and the pressurized air expands to fill that space, the force applied to the dart by that expanding gas will be overcome by the frictional force of the barrel, and the dart will start to slow back down again. However, it's my totally subjective and unscientific opinion that because of the high friction and low mass in most dart/barrel combinations, the margin between the barrel lengths where the dart will begin to slow down and the length where it will come to a complete stop in the barrel is relatively short. So you'll probably know it when you see it happen.

As far as velocity vs range, it is a basic fact of physics that the distance a dart will travel is a function of it's velocity when it leaves the barrel (muzzle velocity). If you're using the same darts, you can't increase the muzzle velocity without increasing the range, and vice versa. You can increase the range of a dart without increasing the initial velocity by reducing drag (air friction) but this is a property of the dart itself and has nothing to do with the barrel. So it's impossible to have a gun with 'good velocity but crappy range'. That didn't really have anything to do with your post, but a lot of people get that wrong.

Edit: The 'barrels' hasbro puts on most of its blasters are probably just for show, and seem slow the dart down if anything. So most of that huge rant probably didn't have anything to do with what you're trying to do. Either way, the rules here are to try it first, then let us know how it goes.

Edited by Langley, 19 October 2011 - 11:19 AM.

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#4 spacephrawg

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Posted 19 October 2011 - 12:09 PM

Very good then I shall do it. Langley you corroborated what I was saying about the Hasbro barrel so it sounds like what I want to try should work. I will try it shortly and report back in a new thread.
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#5 Blue

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Posted 19 October 2011 - 02:23 PM

Since we're on the topic of range and velocity already, can you accurately predict ranges based on chrono readings?
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#6 canuck

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Posted 19 October 2011 - 02:58 PM

Since we're on the topic of range and velocity already, can you accurately predict ranges based on chrono readings?


Perhaps, but then there are a lot of different variables that should be taken into account. Barrel material, darts, even temperature can all have an effect on range.
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#7 Curly

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Posted 19 October 2011 - 03:52 PM

Perhaps, but then there are a lot of different variables that should be taken into account. Barrel material, darts, even temperature can all have an effect on range.

You can, however find out which blasters have higher muzzle velocities, and with the same darts that can give a reasonable estimate of range.

Edited by Curly, 19 October 2011 - 03:52 PM.

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#8 bennorco

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Posted 19 October 2011 - 05:48 PM

Maybe it is just me, but something as simple as a cosmetic barrel doesn't warrant a post.
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#9 SixShot

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Posted 19 October 2011 - 09:16 PM

Hi all

This is SixShot from SG.

(To Mods, please tell me if I am not treading the regulations.)

I have been trying to improve nerf for the past 2 years in the most scientific way possible.

For me, it is a combination of the blaster and dart.

No point having an awesome blaster and less than satisfying darts for ammo.

We all know that adding springs increases the velocity, but the darts accuracy is leaves a lot to be desired.

Using the musket and ball theory and Trebuchet idea, I figured stabilizing the trajectory of the dart might improve some but not in terms of accuracy.

I used a foam dart ( either taggers / sucker darts), took out the head portion, used the stick eraser and glued the eraser in the darts.
( If you guys want, I can post in the appropriate sections later.)

The finished dart is a fairly predictable in terms of trajectory and a MOA ( if that is the correct word to use) of 8 to 10 cm at 10 to 9 meters.

IMHO, that is one of the more achievable ways improving nerf blasters' performance.

Yes, I agree getting a longer barrel might not get better accuracy.
And it annoys me to no end that some players transplant their Counterstrike or whatever FPS beliefs into a Nerf game.

Edited by SixShot, 20 October 2011 - 12:01 AM.

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#10 Daniel Beaver

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Posted 19 October 2011 - 11:09 PM

Since we're on the topic of range and velocity already, can you accurately predict ranges based on chrono readings?



Yes, absolutely. The flight path of the dart is determined by it's initial velocity, mass, and aerodynamic properties. As long as all three of those are the same, it will fly the same distance. The latter two are determined by the dart you are using, and the velocity is determined by the blaster. It is a much better measurement than the standard "it flies 100ft" observations that we make.
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#11 chavez guy

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Posted 19 October 2011 - 11:40 PM

Yes, I agree getting a longer barrel will not get better accuracy.
And it annoys me to no end that some players transplant their Counterstrike or whatever FPS beliefs into a Nerf game.


Dude, it isn't just some videogame fantasy. The idea behind a nerf barrel is that for as long as air (compressed or plunger generated) is pushing on the dart, the dart is in the barrel. But the second the plunger stops moving or the compressed air has all been released, you want there to be no more barrel at that point. So for some guns (HAMPS, big blasts, PASes, +bows, etc.) the absurd ammount of air requires a longer barrel.

Is my explanation making sense to anyone else other than me? Or am I jsut completely off base?
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#12 SixShot

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Posted 20 October 2011 - 12:04 AM

Dude, it isn't just some videogame fantasy. The idea behind a nerf barrel is that for as long as air (compressed or plunger generated) is pushing on the dart, the dart is in the barrel. But the second the plunger stops moving or the compressed air has all been released, you want there to be no more barrel at that point. So for some guns (HAMPS, big blasts, PASes, +bows, etc.) the absurd ammount of air requires a longer barrel.

Is my explanation making sense to anyone else other than me? Or am I jsut completely off base?


I am sorry, I typed wrongly.
It should be: "Yes, I agree getting a longer barrel might not get better accuracy."

You have a point there.

I am keeping an open mind on this issue.

Edited by SixShot, 20 October 2011 - 12:04 AM.

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The Riddle of Foam Blasters;
What is the spring compared to the hand that wields it ?

#13 Darksircam

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Posted 20 October 2011 - 12:22 AM

Really, as long as it's not a tight faux barrel (anything looser than PETG) your ranges won't be hampered much. A millimeter of extra space compared to the main Recon barrel (after the centimeter of tight barrel) is enough.

chavez_guy actually made the most sense to me.

Correct me if I'm wrong, but this is what I understand about barrels from experiments and reading the forums:

Barrel is designed to channel the moving air to push the dart out at optimal velocity.
On smaller volume blasters, you use short tight barrels because there's not enough air volume/pressure to force it out over a longer distance. The tight barrel makes sure all the air stays behind the dart until it exits the barrel, and has greater initial acceleration because the air builds up until the dart just pops out. One way this is accomplished is through telescoping barrels, which are tight for a cm or two and then looser, still allowing for minor acceleration and more stability, but the initial "pop" is when it accelerates the fastest.

With spring mods you can use longer barrels because the spring can push the air fast enough to work with a longer barrel - basically pushing the dart harder.

With airguns you want a long, looser barrel because it optimizes performance. You can afford to lose a bit of air, and that barrel means you lose less energy due to friction.

Homemade springers are kind of like airguns in that they have a lot of air volume. Using small barrels means that it's not nearly done accelerating (increasing in velocity technically) and the air kind of blasts around the dart, messing up its flight path if it's uneven.

HAMPs, Super Soakers, and Titans can use even longer and looser barrels because they output an absurd amount of air. HAMPs can't use tight barrels as airseal is pretty poor in the plunger, you just force a lot of air through really quickly.





Homemade darts help increase accuracy, modding blasters to be able to shoot those darts a good distance increases accuracy as well. Shoot a dart faster and it's less affected by moving targets.
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#14 Doom

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Posted 20 October 2011 - 07:48 AM

In reply to the subject of the first post, if you're talking about porting a barrel, then don't bother. If you have sufficient "back pressure" on the dart when it's leaving the barrel, you should make the barrel longer. This is easy in Nerf and hard in actual firearms, hence why you see elaborate systems to reduce the pressure on exit in firearms.

Since we're on the topic of range and velocity already, can you accurately predict ranges based on chrono readings?


Beaver is correct. If you want an equation, look at equation 5.2 on page 8 of this: http://btrettel.nerfers.com/ebond.pdf

You have to know what the other variables mean, but once you do it's just plug and chug. This should be reasonably accurate for most Nerf darts on average.

(Of course, to nitpick, it can't be chrono readings alone unless your chrono also weighs darts.)

But the second the plunger stops moving [...] you want there to be no more barrel at that point.


This is a misconception that boltsniper probably originated or helped promote. The criterion to maximize muzzle velocity is for acceleration to be zero (and velocity to be concave down, but we'll ignore that). As we know, force is proportional to acceleration. So it really comes down to the second thing you mentioned: the pressures dropping to atmospheric (i.e. all the compression being released).

What the plunger is doing is obviously relevant, but your barrel is far too short if you stop it when the dart reaches a point that coincides with when the plunger stops moving. That point corresponds to maximum pressure (usually) and consequently maximum acceleration, not maximum velocity, which is what we want. You need to wait for the gas to expand to get maximum velocity.
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#15 spacephrawg

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Posted 20 October 2011 - 11:15 AM

Really, as long as it's not a tight faux barrel (anything looser than PETG) your ranges won't be hampered much. A millimeter of extra space compared to the main Recon barrel (after the centimeter of tight barrel) is enough.

chavez_guy actually made the most sense to me.

Correct me if I'm wrong, but this is what I understand about barrels from experiments and reading the forums:

Barrel is designed to channel the moving air to push the dart out at optimal velocity.
On smaller volume blasters, you use short tight barrels because there's not enough air volume/pressure to force it out over a longer distance. The tight barrel makes sure all the air stays behind the dart until it exits the barrel, and has greater initial acceleration because the air builds up until the dart just pops out. One way this is accomplished is through telescoping barrels, which are tight for a cm or two and then looser, still allowing for minor acceleration and more stability, but the initial "pop" is when it accelerates the fastest.

With spring mods you can use longer barrels because the spring can push the air fast enough to work with a longer barrel - basically pushing the dart harder.

With airguns you want a long, looser barrel because it optimizes performance. You can afford to lose a bit of air, and that barrel means you lose less energy due to friction.

Homemade springers are kind of like airguns in that they have a lot of air volume. Using small barrels means that it's not nearly done accelerating (increasing in velocity technically) and the air kind of blasts around the dart, messing up its flight path if it's uneven.

HAMPs, Super Soakers, and Titans can use even longer and looser barrels because they output an absurd amount of air. HAMPs can't use tight barrels as airseal is pretty poor in the plunger, you just force a lot of air through really quickly.





Homemade darts help increase accuracy, modding blasters to be able to shoot those darts a good distance increases accuracy as well. Shoot a dart faster and it's less affected by moving targets.



Thanks for this. So my idea should work but might not be necessary then? I'm going to get two recons and try it both ways just for the hell of it. Either way, the end result will look sort of like an original M4 or Mp44.

I'm really glad the thread hasn't been shut down. I'm sorry for violating the rules but this thread has been extremely educational for me. Thanks to everyone who participated.
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#16 canuck

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Posted 20 October 2011 - 05:28 PM

On a final, (somewhat unrelated note) if you use a barrel of cpvc or brass, do not leave the end of the barrel bare. A few years back a friend of mine by accident of course stabbed me in the side with a copper barrel that broke the skin, but thankfully not to deep. With a few more pounds of pressure, it would really suck.
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We don't have military tactics or specialized training. We're fucking kids playing with plastic guns trying to tag each other.
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