Fps inconsistency

[Vsqs]

Hello! I have a AEG, that is constantly lowering more than 100 fps every couple shots. Any tips of which component is causing this? The gun is a m604e from de armory. It only had the air nozzle switched to this day because the stock one broke after around one year of use. I replaced with a 21.2mm, can you guys confirm if is this the right size as well?

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[Leo Greer]

What ammo are you using?

That is not the right size. 21.4mm is standard for most replicas.

If this issue didn’t occur before you switched the nozzle, I would try and find a generic 21.4mm nozzle to switch to, or if you feel like it, a Maxx adjustable.

First, however, you should get inside the barrel group and make sure you don’t have grease or something else on the hop rubber, nozzle, or anything outside the gearbox, really.

 

[AirSniper]

You have to account for a recovery time from the battery dumping a load of energy in to the winding motor, you have to account for cycling time, you have to account for friction, account for the BB's not being precision sizes, some are ever so slightly larger and smaller which affects the ability to transfer energy.

There are other factors that also can affect fps, hop up, dirty barrel, lubrication and the chrono can misread which is why you take multiple readings to get the average fps.

 

[Leo Greer]

You have to account for a recovery time from the battery dumping a load of energy in to the winding motor, you have to account for cycling time, you have to account for friction, account for the BB's not being precision sizes, some are ever so slightly larger and smaller which affects the ability to transfer energy.

There are other factors that also can affect fps, hop up, dirty barrel, lubrication and the chrono can misread which is why you take multiple readings to get the average fps.

Where are you getting this info?
 

The battery has nothing to do with FPS… unless you’re running too high of voltage and are getting PME.

Cycling time also has nothing to do with FPS…

Friction of what?

I’ve measured over a dozen different brands of BBs, both weight, sphericity, and checked for air bubble consistency on the inside. Not even horrible green BBs from sporting goods stores had enough size or weight inconsistency to cause any FPS variance like this. This would require some of the BBs to be literally double the weight. For reference, even low quality BBs like Lancer Tactical have weight variances that are in the hundredths of a gram.

Dirty hop unit, and dirty barrel… yes. Except it’s only happening with certain BBs, and the drops are consistent.

The chrono can misread, but averaging in giant drops like this isn’t accurate.

This does bring up a valuable point, though—OP, is it possible you mixed heavier BBs in with your .20gs? They would have to be really heavy, like .40g+. I realize that’s not at all likely, but it’s a possibility nonetheless.

 

[Cannonfodder]

Where are you getting this info?

He's got a habit of posting tech advice which is complete bollocks

 

[Lozart]

He's got a habit of posting complete bollocks

FTFY

 

[Leo Greer]

He's got a habit of posting tech advice which is complete bollocks

Next time I’ll just quote his post say in all caps “OFFICIAL BOLLOCKS MARK”

 

[Cannonfodder]

Next time I’ll just quote his post say in all caps “OFFICIAL BOLLOCKS MARK”

If you really want a laugh go look at his ballistics thread

To the OP. It sounds like you've got a problem with the nozzle getting a good air seal intermittently 

 

[AirSniper]

Where are you getting this info?
 

The battery has nothing to do with FPS… unless you’re running too high of voltage and are getting PME.

Cycling time also has nothing to do with FPS…

Friction of what?

I’ve measured over a dozen different brands of BBs, both weight, sphericity, and checked for air bubble consistency on the inside. Not even horrible green BBs from sporting goods stores had enough size or weight inconsistency to cause any FPS variance like this. This would require some of the BBs to be literally double the weight. For reference, even low quality BBs like Lancer Tactical have weight variances that are in the hundredths of a gram.

Dirty hop unit, and dirty barrel… yes. Except it’s only happening with certain BBs, and the drops are consistent.

The chrono can misread, but averaging in giant drops like this isn’t accurate.

This does bring up a valuable point, though—OP, is it possible you mixed heavier BBs in with your .20gs? They would have to be really heavy, like .40g+. I realize that’s not at all likely, but it’s a possibility nonetheless.

Batteries have a load and recovery time... physical fact.

The motors cycling the piston ram take time, each actuation takes energy, the more energy you pull from a cell, the slower the BB's get

BB's are not perfectly round and do not seal, escaping air will impact as well on the speed.

For example, the chron at my game yesterday read 349,329,322,311 with 4 rapid shots through the chrono, ALL AEG's will have progressively slower output unlike HPA.

A dirty barrel will also cause loss of fps as power is dissipated in the barrel because of drag.

As for the OP, if you run some of those readings through a calculator, a fair few of them run in to an issue with being over the legal 1.3 Joule maximum (aka firearms offence) assuming a standard 0.2g BB and not a 0.18g variety.

393 fps @ 0.2g = 1.43 Joule

384 fps @ 0.2g - 1.37 Joule

376 fps @ 0.2g = 1.31 Joule

So either the Chrono is faulty or someone has a naughty RIF.

 

[Leo Greer]

Batteries have a load and recovery time... physical fact.

The motors cycling the piston ram take time, each actuation takes energy, the more energy you pull from a cell, the slower the BB's get

BB's are not perfectly round and do not seal, escaping air will impact as well on the speed.

For example, the chron at my game yesterday read 349,329,322,311 with 4 rapid shots through the chrono, ALL AEG's will have progressively slower output unlike HPA.

A dirty barrel will also cause loss of fps as power is dissipated in the barrel because of drag.

As for the OP, if you run some of those readings through a calculator, a fair few of them run in to an issue with being over the legal 1.3 Joule maximum (aka firearms offence) assuming a standard 0.2g BB and not a 0.18g variety.

393 fps @ 0.2g = 1.43 Joule

384 fps @ 0.2g - 1.37 Joule

376 fps @ 0.2g = 1.31 Joule

So either the Chrono is faulty or someone has a naughty RIF.

That’s not the battery—that’s your replica having issues.

The motor pulls back the piston. That’s it. Why would how fast you pull back the piston affect FPS in any way? It’s how fast the piston moves after the sector releases.

A dirty barrel may cause lower FPS, but it can also cause higher FPS. It depends on what kind of “dirty” you’re talking about. For example, BB residue can cause a barrel to functionally become tighter, which increases FPS.

 

[RostokMcSpoons]

That’s not the battery—that’s your replica having issues.

The motor pulls back the piston. That’s it. Why would how fast you pull back the piston affect FPS in any way? It’s how fast the piston moves after the sector releases.

A dirty barrel may cause lower FPS, but it can also cause higher FPS. It depends on what kind of “dirty” you’re talking about. For example, BB residue can cause a barrel to functionally become tighter, which increases FPS.

Air sniper, read and learn ?‍???

 

[Colin Allen]

Air sniper, read and learn ?‍???

He won't.

 

[Leo Greer]

BB's are not perfectly round and do not seal, escaping air will impact as well on the speed.

Correct. But they’re so close that it doesn’t matter. I measured three brands of BBs of low, medium, and high shooting quality, with a micrometer and then charted the results.

BLS .32g scored the highest, having only a single variation. Lancer Tactical .20g we’re the worst, and yet the variation was still minuscule.

Here were my results for the BLS, using 10 BBs picked at random (in inches):

0.234”

0.234”

0.234”

0.234”

0.234”

0.234”

0.2335”

0.234”

0.234”

0.234”

Equivalent: 5.9436mm on average.
 

And here were my worst results, for Lancer Tactical .20g:

0.234”

0.2335”

0.233”

0.2335”

0.2335”

0.233”

0.2335”

0.2335”

0.233”

0.233”

Equivalent: 5.92709mm on average.

 

[AirSniper]

Correct. But they’re so close that it doesn’t matter. I measured three brands of BBs of low, medium, and high shooting quality, with a micrometer and then charted the results.

BLS .32g scored the highest, having only a single variation. Lancer Tactical .20g we’re the worst, and yet the variation was still minuscule.

Here were my results for the BLS, using 10 BBs picked at random (in inches):

0.234”

0.234”

0.234”

0.234”

0.234”

0.234”

0.2335”

0.234”

0.234”

0.234”

Equivalent: 5.9436mm on average.
 

And here were my worst results, for Lancer Tactical .20g:

0.234”

0.2335”

0.233”

0.2335”

0.2335”

0.233”

0.2335”

0.2335”

0.233”

0.233”

Equivalent: 5.92709mm on average.

It doesn't take much...

I shoot airguns and I buy 4.52 or 4.53 sized pellets because they work better because of the extra snug fit. A standard 4.5 pellet can vary slightly and the variance of 0.02 can have a big effect on the pellets performance. Air can get past a pellet that is ever so slightly undersized like it can with a BB and a barrel that is not a consistent size ID.

Same goes for BB's in airsoft, whilst the BB's may be within a specific tolerance, are the barrels? Unless you are buying a custom made to a specification sized bore, you are at the whim of the machinery that formed the tube that makes your barrel including any deformities no matter how small they are, any blemishes and corrosion.

People may scoff all they like, it takes very little to change a BB's performance, which is why you clean your barrel between games, to minimise particulates that have entered the barrel.

Anyone who has played at a dusty site will know that the cleaning wad comes out dirty.

The exact same issue with powder firearms exists, which is why you clean them after a shooting session and also a regular weekly clean to prevent corrosion build up in the barrel which is the leading cause of gun failure.

 

[Leo Greer]

It doesn't take much...

I shoot airguns and I buy 4.52 or 4.53 sized pellets because they work better because of the extra snug fit. A standard 4.5 pellet can vary slightly and the variance of 0.02 can have a big effect on the pellets performance. Air can get past a pellet that is ever so slightly undersized like it can with a BB and a barrel that is not a consistent size ID.

Same goes for BB's in airsoft, whilst the BB's may be within a specific tolerance, are the barrels? Unless you are buying a custom made to a specification sized bore, you are at the whim of the machinery that formed the tube that makes your barrel including any deformities no matter how small they are, any blemishes and corrosion.

People may scoff all they like, it takes very little to change a BB's performance, which is why you clean your barrel between games, to minimise particulates that have entered the barrel.

You’re not wrong about a performance change existing, but it’s genuinely unnoticeable in any way. There’s no point in fighting what you can’t tell exists.

The point is not to allow no air to pass. Comparing the physics of airsoft BBs with air gun pellets is apples to oranges. BBs make use of the Magnus effect, literally riding on a cushion of air through the barrel. In fact, many airsoft techs believe that a wider bore can increases accuracy, as it allows for more space between the barrel and the BB, so any inconsistencies that may exist are cushioned. This hasn’t been proven to be true, but tighter bores aren’t proven to be more accurate either.

A good barrel will be precision made, same as good BBs are precise. Many good aftermarket barrels are made using cold forging by hammer and mandrel, same as many, many firearms. In fact, some stock barrels are now made to PCP standards, using PCP processes.

 

[Lozart]

Batteries have a load and recovery time... physical fact.

The motors cycling the piston ram take time, each actuation takes energy, the more energy you pull from a cell, the slower the BB's get

The rate of fire will slow down but the actual muzzle energy is NOT affected by the speed of the gearbox cycling unless it is cycling so fast as to cause pre-engagement. Once the sector gear lets go of the piston rack it's purely down to the main spring to provide the motive force.

Yes, surface imperfections on the BB and dirt on the barrel can impact performance but as @Leo Greer mentioned the difference in FPS is minimal unless the BBs are awful or your barrel is basically blocked.

If an AEG is firing with progressively lower muzzle energy then it won't be caused by the battery or the speed of the motor. Equally your statement that ALL AEGs do this is patently false and most likely observation bias.

 

[Shamal]

I guess that if you put a crank handle on the gears and manually wound the mainspring back until it realeased then the piston would push the BB out at same FPS but with no volts being involved. So that would prove that the battery state is not directly responsible for FPS.?

Regards 

 

[Colin Allen]

The power spring in an airsoft gun is a mechanism for storing energy.  When the spring is released, that energy is expended in overcoming whatever is preventing the spring returning to its pre-compressed length, which can be friction in the guide rails or between the piston head O ring and the cylinder, or air resistance.  Provided that the spring is always compressed to the same length, the energy stored will always be the same, regardless of how that compression is achieved, assuming that the spring strength remains constant..

 

[Cannonfodder]

The power spring in an airsoft gun is a mechanism for storing energy.  When the spring is released, that energy is expended in overcoming whatever is preventing the spring returning to its pre-compressed length, which can be friction in the guide rails or between the piston head O ring and the cylinder, or air resistance.  Provided that the spring is always compressed to the same length, the energy stored will always be the same, regardless of how that compression is achieved, assuming that the spring strength remains constant..

This. A lower voltage battery (whether it's a 7.4v compared to an 11.1v, or a dying battery compared to a fresh one) will cycle the GB slower but not affect the fps. The muzzle energy is down to the potential energy in the compressed spring

 

[AirSniper]

The power spring in an airsoft gun is a mechanism for storing energy.  When the spring is released, that energy is expended in overcoming whatever is preventing the spring returning to its pre-compressed length, which can be friction in the guide rails or between the piston head O ring and the cylinder, or air resistance.  Provided that the spring is always compressed to the same length, the energy stored will always be the same, regardless of how that compression is achieved, assuming that the spring strength remains constant..

Springs wear out, you know your car uses many springs and over time and repeated use through compression and release cycles, they break or loose their ability to provide the required resistance or force.

Same for any spring, some springs are made better than others and some are not and in airsoft, don't expect the best quality. Remember where they are made and the type of steel that is used isn't the same as home grown steel.

In Airguns you expect something that lasts the lifetime of the rifle but even then, they can fail, my sons HW57, a springer .177 had a failure of the spring because the rifle dieseled and caused the spring to become over stressed and it turned a sub 12 fpe in to a sub 8 fpe rifle.

Springs do fatigue and lose their elasticity / tension strength and if you have an ETU that applies precocking to the piston, your spring is under pressure waiting for that release to relax. I had this problem in my RIF where I had the precocking set but didn't let the tension go and what happened was the ratchet and spring went, I had to have a new spring and piston.