.25 vs .20 chrono in aeg with excess cylinder volume

[thekonassure]

A while back there was a bit of talk over .20`s and .25`s and the difference you may get when using them

Well I just did some testing on an aeg I have that is used as a loan out and back up gun.

It has a very short barrel and a full cylinder in the gearbox so its pretty loud when shot as there is a lot of wasted air but its a back up so who cares

Anyway I chrono`d up some .25`s and .20`s on this gun

My chorno was set to .25 for the .25`s and the results in J were all around the .90 J to .92 J

The chrono was then set to .20 and a new mag with .20`s was loaded into the gun the result was .81 J to .84 J

So it seams that even a short barrel aeg can have an out put of around 10% more muzzle energy when using .25`s over .20`s

I also did some testing on my WA 6" infinity

With .20`s I was getting around 1.1J and with .25`s closer to 1.3J but the gun had just been rebuilt and re-lube`d so I`d want to wait a few 100 rounds before I gave merit to these results.

I may do some more testing on gas guns but as my WE PDW is still very new I want to wait till the hop is bedded in before using it to test this theory, but I have also noticed on that around 10% more muzzle energy with .25`s

Maybe this factor is less in longer barrel guns ?

It may also be as simple as pushing a heavy bb is easier as its not going to fast so has more time in the barrel to ride the air wave and get accelerated up to speed ?

I may order some .30`s .40`s and 1g bb`s but I find most bb`s over .25 to be really expensive for what you get and as I`m no sniper I don`t see the point in spending the extra money.

Anyway that`s what I`ve been up to today now let the arguments commence lol

[The General]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

Heavier ammo retains more energy. No surprise there.

[Nomad]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

Yeah Im not quite sure what this thread is proving other than the already commonly known? :P

[Spooros]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

Might be the fact that guns are tested on .2s and these results show that just by a change of weight you are upping the energy.

[Major]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

Surely this is like being AMAZED when finding out that a truck moving at 60mph carries more Energy than a small child moving at 60mph?
It's just logic

[ElCarl]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

Surely this is like being AMAZED when finding out that a truck moving at 60mph carries more Energy than a small child moving at 60mph?
It's just logic

No, as the spring only transfers a certain amount of energy.
It turns out that in this system, using .25s transfer more of that energy into the BB.

[Fiberoptikz]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

if you want to do something interesting go chrono your PDW on .20s, .25's and then .3's and see what the results are.

[JOE90]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

No, as the spring only transfers a certain amount of energy.
It turns out that in this system, using .25s transfer more of that energy into the BB.

Yeah what hes saying for example a 1j spring transfer roughly a joule of energy to a.2 bb, but oddly manages to transfer more than a joule into the .25,When a normal mind would think a heavier bb would take away some of the force needed to push the heavier weight out the barrel. but instead its given more joules than expected. I dont understand why but i think thats what he was getting at.

[The General]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

This is so easy to explain.

Heavier weight means it retains more energy, also heavier weight means its in the air system longer allowing it to achieve this greater energy level.

In plain English, its heavier so its in the barrel longer and thus gaining more.

Gas weapons are particularly and very noticeably effected by this with heavier bb's.

The spring is just that, a spring. You cannot say a spring is a 1J or a 100 Meter per second spring in truth as there are far too many variables. Its just a rough estimate. I have seen perfectly set up guns get 390 fps on .20's with an M100 spring. Next you will be telling me that's a mystery?:D

[JOE90]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

The reason gas guns are affected by longer barrels is because the gas has more time to expand, didnt think this happend with air but you pretty muche explained it for me. thanks

[balaclava ben]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

the larger increase in energy in the WA infinity would be partly due to the expansion of gas whilst the heavier bb is travelling dow the barrel, with a .2 BB obviously leaving the barrel faster than a slower travelling .25 BB. This slightly longer time spent in the barrel allows more of the continually expanding gas to transfer more of its energy to the BB and therefore increase the measured energy in comparison to the BB.
All that aswell as the heavier BB retaining it's kinetic energy better than the .2

Edit: Seems like all three of us are on the same wavelength...

[thekonassure]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

.30`s too expensive or I would get some and some heavier bb`s too and test them on my pdw

I`d also test on green gas and co2 too as my guess is on a hot day propane will expand more down a barrel then co2 will.

I`ve also had a well set up aeg getting 390fps on an m100 spring before but I never bothered to see if it was getting more or less muzzle energy with a .25

Anyway I just remember there was a thread a while back and people were saying that putting a .25 in an aeg would not up the muzzle energy.

I think if your cylinder volume is tuned very finely for a .20 bb then you will not get much more benefit from a .25 ?

[MUCKYMICK]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

do we have to go through this all over again your theory is completly wrong the only thing effecting the impact energy of the bb is it weight the heavier the bb the more mass it will carry when it is accelerated over any given distance.
heavier bb's will travel slower ,have more impact energy at the muzzle and will loose energy much faster so will not travel as far than lighter bb's, it has nothing to do with how long the bb take's to leave the barrel when fired with the same amount of force/propellant its traveling slower so it going to take longer to exit the barrel.
Not really sure why the op keep's bring fps a bb weight up it's commonly known how bb weight effect's fps and impact energy reading when chronoed at the muzzle that's why all sites have limit's and measure that limit with .2 bb's.

[thekonassure]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

Well application to a game site is that we say 330fps or 350fps on a .20 as a site limit so around 1j where as it seams if you were to load a .25 into that same gun it would be shooting at 1.1J to 1.2J to me that would be a "hot" gun.

So why do sites insist on .20 to chrono with but then let players use any ammo weight they want ?

[balaclava ben]

Re: .25 vs .20 chrono in aeg with excess cylinder volume

the heavier the bb the more mass it will carry when it is accelerated over any given distance

mass is not variable - therefore your statement is incorrect.

heavier bb's will travel slower ,have more impact energy at the muzzle and will loose energy much faster so will not travel as far than lighter bb's

Correct, correct, wrong. A heavier BB will retain it's energy/momentum better than another of lighter mass when the same propelling force is applied to it.

it has nothing to do with how long the bb take's to leave the barrel when fired with the same amount of force/propellant its traveling slower so it going to take longer to exit the barrel.

well it does! compressed gases take a suprisingly long time to fully expand. A lighter BB tends to leave the barrel just before the gas is fully expanded and therefore the continually expanding gas does not transfer all it's energy to the BB. By travelling down the barrel slower, like you say here,

its traveling slower so it going to take longer to exit the barrel.

the gas has more time to impart all of it's potential energy onto the BB.

So why do sites insist on .20 to chrono with but then let players use any ammo weight they want ?

i think it's simply because it's not widely known that this effect takes place when using gas guns