First of all, it's "source", not "cylinder"- some of us are HPAholes :yup:

Primary Intrigue:

Is there convincing evidence that the "ideal" (creates the most muzzle energy- adjusting barrel length causes reduction) source/barrel volume ratio also creates the most accurate/precise trajectory?

I've heard confident talk about how it does- even specifically that a smaller ratio can be worse than a larger ratio. In the most intuitive way, I suspect it's true, but due to the following logic, I have to wonder if a smaller ratio is actually negligible (then there's the alternative theory on why CJ barrels work well- indicating larger ratios may be

*better*...).

The concern with decreasing the ratio - as I understand it - is that the BB starts to lose that considerable pressure on its back as the source volume expands (filling the volume behind the BB), causing the BB to destabilize. However can this actually be significant [when the ratio is greater than 1]? It seems to me that the following graphic/explanation would illustrate that if this does occur (destabilization as pressure behind the BB decreases), it should be a sloped issue, and not a binary transition from good to bad.

Let's assume the BB weight's ideal ratio is 2, or 2:1 (this logic can be applied to any realistic ideal ratio, as we see they're always greater than 1). The rifle on top has a ratio of 4:2- ideal. The rifle on bottom has a ratio of 4:3- less than ideal. However in both systems, the BB has expanding air behind it through the BB's breach.

Also of note, If we try to compare the energy output of the top system to the bottom using different chronograph measuring points A and B, we might see that the top has a higher muzzle energy, but that would be an invalid comparison; if the source volumes are equal

*and the volumes of air behind the BBs are both still expanding through muzzle breach*, is it actually possible for the top system to impart a higher velocity on the BB measured at point B compared to the bottom system? It seems the answer would be 'no'- increasing barrel then, cannot

*truly* be said to reduce system power output objectively (just an interesting consideration when we think about what an "ideal" source/barrel ratio means).

Discerning Ideal Source/Barrel Ratio

*(i.e. barrel length)* Based on Input BB Weight:

I made this:

Based on 1tonne's data:

https://www.airsoftsniperforum.com/...der-barrel-ratios-explained-8.html#post336554
(the exponential extrapolation had the best fit)

Bonus Question:

Please, someone tell me I'm stupid and explain to me the following...

We have a data set that gives us "golden truth" data on the ideal source/barrel volume ratios for a few combinations of BB weight and barrel length using a given source volume.

There are four columns of data in that set; we know we care about BB weight, but there is the ideal ratio, the barrel length, and the barrel volume. So let's look at a couple ways one could use this data to extrapolate for other BB weights not tested...

Say Bobby looks at this data, and knowing his cylinder size is the same as the data source's, chooses to simply plot the barrel lengths and BB weights. Using a linear trend line to extrapolate, he discerns an equation to calculate the barrel length he would need for BB weight X.

Now Cottonswabby looks at the data, but she instead chooses to plot the actual ideal ratios and BB weights. She

*also* uses a linear trend line to extrapolate, discerning an equation which will allow her to calculate an ideal source/barrel ratio number, which she can then use with her known cylinder size to calculate the barrel length

*she* would need for BB weight X.

Now, if both Bobby and Cottonswabby's methods of calculating the ideal barrel length for BB weight X use data from the same controlled set, extrapolated linearly, then why do they get different results?

And why would someone name their child Cottonswabby?

Basically you can create a trend line based on [BB weight and] barrel length OR ideal ratio- and if you do so, you'll find that the two resulting methods suggest

*different* barrel lengths for input BB weight X.

- Is Bobby wrong because his extrapolation was based on only half (barrel length) of the integral value (ideal ratio)?

- Is Cottonswabby wrong because her extrapolated results were used in conjunction with a

*different* source volume than the original data set's?

- Am I so far off base none of this makes sense?

Maybe I'm just tired- I feel like the answer is obvious. Pretty sure Cottonswabby is right.