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Ideal Source/Barrel Volume Ratios Based on BB Weight: The Implications?

11554 Views 29 Replies 6 Participants Last post by  MagicMarker, 
MagicMarker
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.
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Zero Roaster
'Cottonswabby'...:cheers::lmao::tup::bow:

Now what was the question?!:shrug: I'll have to think about it once I stop laughing. Man that's funny!!!!:funny:
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Zero Roaster
OK, so having reread the question a few times, I still don't think the ratio is the end all and be all of getting a BB to go straight. There's still a lot more to it than that. For example, the BB goes through different phases from the time it climbs up the feed tube to the time it exits the barrel. You even have to take into account overcoming the friction of the mag spring as this will have an affect on the amount of energy coming out of the gearbox and the ability to move the BB regardless of the barrel ratio.

In theory, you can look at volumetric ratios and discern that Cottonswabby's rig is ideal, or is it? You have to bring in losses from the system. The rate at which the system chambers the BB, is it in position when the air shot happens, how about the losses surrounding the nozzle to bucking connection? Then there's the velocity changes from the rate at which it's chambered, then the braking effect of the hop up induced to the BB, then the ability of the system to allow the BB to accelerate once backspin is induced....speaking of which, what about the lift being generated inside the barrel? Is all the air moving forward or do we have a percentage of reverse flow because of lift? This would be calculated based on fps and weight of course...what about the percentage of backspin lost due to friction? Barrel stability? How about temperature? Altitude? Relative humidity? Atmospheric density? Sounds goofy, but it's all in there. How the gas compresses and the rate at which it does so is affected by a whole bunch of conditions....which in turn will affect the BB.

You can continue to break down the process of losses throughout the firing process and may find that ratio is theoretical at best. Another thing that seems to be left out of the equation is the elasticity of the gas. The rifle is not a hydraulic system. There's a compression rate to take into account, and then the expansion on the other end of the nozzle. Do things like the change in orifice size create eddys in the gas? So, the list of things in the chain that continue to affect trajectory and stability go on and on and on...I wish it was as simple as ratio...but it's a decent place to start!!!
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1tonne
Wow. Even I am lost in that question.
Anyway, I should probably explain how I came up with those ratios.
First I had a long inner barrel of 554mm x 6.03mm long. I fired every bb weight with the bb flying straight to 65 meters (I think this was the distance. So long ago) and I recorded the energy rates. I then cut the inner barrel down by 10mm and repeated the process and recorded the energy rates. Then I cut the barrel down some more and repeated the process. I done this all the way down to about 250mm. So the cylinder ratios are from actual experiments. Not just guess work.
Note: First experiment I only cut 4mm to round it to the nearest 10mm.

This is all a guideline but it is one that I use in every build and I recommend these ratios for others when using bolt action rifle.

So I noted that if a barrel became too long for the heavy bb, lost energy and in extreme cases, like a 0.45gm in a 554mm barrel, the accuracy went out the door especially at range.
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Leetworld
Was there wind? I expect as much at 65m distance, but I guess it shouldn’t affect end results much. Anyway, I’ve been also wondering about energy loss per distance. Been reading on it, but got nothing substantial and factual, only a personal guess that bb loses half or more energy after half of it’s “effective” range. I say effective but I mean around 80m hitting reasonable plot, like 1m^2 or say human sized square~. And by hitting I mean bb just dropping there, and only aiming straight not like a mortar. So if bb shoots 100m~, 80m of it is reasonable to expect a hit and after 40m~ lose half of it’s energy or more. This is all rough ideas. But I again guestimate up to this point my theory is fine.
Judging by bullet drop and...
Me and my friends, shot ourselves with our guns after we chronoed, my 175m/s 0.2g at 40m hit me in the back at the same~ish power (hurt) as 125m/s 0.2g aeg at 10m (? needs further research).

Thinking about putting a chrono at 5m and trying to shoot thru it, then at 10m and 15m and so on, until it’s not possible for me to hit it, to get a feeling of energy changes.
Or go myhtbusters on it, make a slob of something and shoot it at same varying distances to see how much it penetrates and compare.

Anyway, anyway, anyone got more ideas?
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wyz2285
better not bring HPA into this, they are always massively over volume.
In a spring powered system the volume is fixed by the cylinder size, the spring just compress it momentarily to transfer it's energy to the projectile.
For wolverine and mancraft, even though the chamber size is fixed and smaller than a standard cylinder, when you pressurize it you're not compressing the existing air only, you are injecting more air into it, 120 psi would be 8 times the existing volume. For polar star you need to calculate the flow rate (l/s) times the opening time (ms).
This is the main reason why I abandoned HPA, it's vastly inefficient.
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Zero Roaster
Leetworld said:
Was there wind? I expect as much at 65m distance, but I guess it shouldn't affect end results much. Anyway, I've been also wondering about energy loss per distance. Been reading on it, but got nothing substantial and factual, only a personal guess that bb loses half or more energy after half of it's "effective" range. I say effective but I mean around 80m hitting reasonable plot, like 1m^2 or say human sized square~. And by hitting I mean bb just dropping there, and only aiming straight not like a mortar. So if bb shoots 100m~, 80m of it is reasonable to expect a hit and after 40m~ lose half of it's energy or more. This is all rough ideas. But I again guestimate up to this point my theory is fine.
Judging by bullet drop and...
Me and my friends, shot ourselves with our guns after we chronoed, my 175m/s 0.2g at 40m hit me in the back at the same~ish power (hurt) as 125m/s 0.2g aeg at 10m (? needs further research).

Thinking about putting a chrono at 5m and trying to shoot thru it, then at 10m and 15m and so on, until it's not possible for me to hit it, to get a feeling of energy changes.
Or go myhtbusters on it, make a slob of something and shoot it at same varying distances to see how much it penetrates and compare.

Anyway, anyway, anyone got more ideas?
Click to expand...
Ok, so a projectile has more than one vector acting upon it. You have drag from the forward direction and gravity from the bottom, so in essence you're on the right track. Deceleration is not linear, it's a curve. The gravity vector is constant, but the drag plus the friction of air on the surface of the BB plus the loss of rotational inertia as the energy of the backspin wears off, makes for a progressive loss of energy. I won't even sort of bother with the math..Hehehehe.

In the end, although the air discharge is critical to launching a BB, it isn't absolute in determining the final results of the flight.

Sent from my iPhone using Tapatalk
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J
Good post. It's good to look at our assumptions in perspective.


I think that while all the math is correct, the initial numbers that it relies on is not fully representive, and therefor does not apply correctly.


I think many people are just blinded by the effects of joulecreep and don't realize it is actually inefficiency with a light BB rather than efficiency with a heavy BB.


Going away from that, there are SO many factors in a spring setup it's crazy. BB weight, nozzle ID, cylinder ID, spring type, spring length, stroke length, pressure lock, barrel length etc...


So just going blindly by volume numbers doesn't matter. You can have the same volume in two different setups (short cylinder + wide piston vs long cylinder + narrow piston) and they will behave differently.


I'm really looking forward to the HTI. It is fairly normal stroke length, but the piston ID is MASSIVE. Like 40mm or something. So it will have crazy airspeed.


I tried shooting it with 4,5J spring last weekend and it was super soft to pull. It's gonna be the number 1 high power rifle. Very quiet even at high energy.
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MagicMarker
Zero Roaster said:
[...]
Click to expand...
I do understand there are a ton of variables to take into consideration, and many are unavoidable, however my post is intended to regard BASRs only - which removes a a considerable amount related to automatic systems - and it's just for discussion on this one topic which seems to be at least one of the most noted tunes to keep in mind when building a rifle.
I know there are endless things to worry about, but it seems volume tuning is agreed upon to be significant, which is why I wanted to dig in a bit.

1tonne said:
Wow. Even I am lost in that question.
Click to expand...
I edited it considerably, so maybe now it's more readable :p

wyz2285 said:
better not bring HPA into this, they are always massively over volume.
Click to expand...
I'm at work at the moment (sh don't tell), but I've tested and discerned the volume outputs of my Tanaka M40A1 and multiple tunes of my Wolverine Bolt; if it's within reason to extrapolate 1tonne's findings to builds of different source volume size, then actually my gas rifles are better volume tuned for heavyweight BBs than most any standard-configured spring sniper rifle (this is because an average spring sniper rifle has far too long a barrel for heavy BBs).
I'll come back and post the source output volumes when I get home.

Jeppe said:
I think that while all the math is correct, the initial numbers that it relies on is not fully representive, and therefor does not apply correctly.
[...]
Going away from that, there are SO many factors in a spring setup it's crazy. BB weight, nozzle ID, cylinder ID, spring type, spring length, stroke length, pressure lock, barrel length etc...
So just going blindly by volume numbers doesn't matter. You can have the same volume in two different setups (short cylinder + wide piston vs long cylinder + narrow piston) and they will behave differently.
[...]
I'm really looking forward to the HTI. It is fairly normal stroke length, but the piston ID is MASSIVE. Like 40mm or something. So it will have crazy airspeed.
Click to expand...
1. Are your thoughts that 1tonne's tests can't apply to differing source/cylinder volumes? His tests were quite conclusive mathematically- certainly a small sample size, but in terms of volume ratio only (we're not getting into the million other variables), it's pretty much objective/conclusive data to use for someone with the same source volume using a BB weight within the data set range.

2 and 3. The HTI is the reason I laid down to sleep the other night and had my brain flooded with airsoft. And your note about all the other specs that can play a part was something I planned on making another discussion for :p
I am also VERY intrigued by the HTI...
- I've always loved the feel of my incredibly well-built Tanaka, immeasurably more than the VSR's pathetic garbage toy feel; I'm assuming the $800 HTI will be built amazingly
- I'm learning I really hate not having a more natural grip on the rifle (like a pistol grip)
- I have a lurking suspicion that my HPA platform could be inherently flawed due to gas power causing an undesirably abrupt increase in pressure upon trigger pull (bad for consistent hop-up / accuracy?)
- My girlfriend forgot we were casually saving for a trip, so now I'm way ahead of her and the money is burning a hole in my pocket! :lmao:
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wyz2285
HPA systems uses more air, however at considerably lower pressure than the peak pressure reached by a spring system. So despite the huge quantity of air, there isn't enough energy stored in it; even with the max valve opening time and a massive barrel the bb won't go supersonic, the low pressure limits the expansion rate.

Gas guns are even harder to figure out as the gas passes through two fases, liquid and gas. A well designed gas system should deliver just the right amount of already in gas state gas to accelerate the bb (that's why some gas guns can be very consistent). It is still a less consistent propellent than air though.

For the same volume and spring power, smaller ID will deliver the highest pressure, not the other way around.
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J
1: It ignores too many factors to be useable for me. I don't pay it much attention, and when i do, it doesn't really match what i see.



HTI:
Yes it's amazing. They have some brilliant people working there who are good at improving their product.
The HTI has a slope/ramp at the end inside the body, so the cylinder head rides in a curve and directs the forward force so the handle naturally locks. It means it loads the BB slowly and you don't slam the cylinder forward. It feels very naturally also after a couple of tries.


I think it will shake up the high power sniper market.
I put a ton of effort into my long-range-only VSR and the HTI will smoke it completely. Doesn't hurt either that it's bullpup so you get more barrel length.


I don't think the pricetag will be a hinderance for people who aim for highend from the start.



It takes 100% the same hopup/barrel as SRS, which i guess is fine since it works.
But i could definately see myself making some sort of combined hopup/barrel thing for it like i've talked about before. Would be interesting to run it with a super high pressure lock and heavy piston (even the stock "light" one is 100gr) and see what it does.



The downside, for me, is that i can't do the same low prone as i can with VSR.
But if i have 50m+ MED maybe that's not a problem anyway...
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1tonne
In my opinion, it does not matter if the cylinder is wide and short or long and narrow. What matters is the volume of air coming out of the air nozzle and the pressure it comes out at. If both have the same volume of air coming out and the pressure is the same coming out of the air nozzle, then you would think that both setups would need the same inner barrel.
Now there are variations in the setup as you will most likely need springs with different tension on them for air pressure to be the same but this is a minor thing.
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MagicMarker
wyz2285 said:
HPA systems uses more air, however at considerably lower pressure than the peak pressure reached by a spring system.
[...]
even with the max valve opening time and a massive barrel the bb won't go supersonic
[...]
For the same volume and spring power, smaller ID will deliver the highest pressure, not the other way around.
Click to expand...
1. Hm, didn't know that- a bit un-intuitive to me actually. Where are you getting this information from?
2. Why would you want a supersonic BB?? Lol- sounds like a fun project but... :nuts:
3. Can you elaborate? Is there some material I can read on this? I think I can understand why this might be the case, but it is sort of news to me- I would say it's intuitive to assume equal volumes with equal power pushing air out would create equal flow rate (pressure) regardless of dimensions.

Jeppe said:
1: It ignores too many factors to be useable for me. I don't pay it much attention, and when i do, it doesn't really match what i see.
[...]
The HTI has a slope/ramp at the end inside the body, so the cylinder head rides in a curve and directs the forward force so the handle naturally locks. It means it loads the BB slowly and you don't slam the cylinder forward. It feels very naturally also after a couple of tries.
[...]
Would be interesting to run it with a super high pressure lock and heavy piston (even the stock "light" one is 100gr) and see what it does.
Click to expand...
1. Huh- so one of my main concerns is probably true- the data may not be useful at all for source volumes differing from that of what was used in the tests. Guess I may just have to commission a cheap super-long barrel and do my own cut-down test to find ideal ratios for my actual rifles...
2. How does it feel? Resistance slightly increases as you push the bolt forward?
3. What do you mean by high pressure lock? I was also going to dig around for education on piston weights, as I understand the general idea of why heavier is used for joule creep, but it's not something I've ever needed to concern myself with- what variables need to be taken into consideration when deciding the weight? Or is there basically no way to go too heavy?
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MagicMarker
1tonne said:
In my opinion, it does not matter if the cylinder is wide and short or long and narrow. What matters is the volume of air coming out of the air nozzle and the pressure it comes out at. If both have the same volume of air coming out and the pressure is the same coming out of the air nozzle, then you would think that both setups would need the same inner barrel.
Now there are variations in the setup as you will most likely need springs with different tension on them for air pressure to be the same but this is a minor thing.
Click to expand...
This is definitely what I was thinking. Assuming the springs release the same energy over their travel, the flow rate through the nozzle and pressure should be identical, no? Maybe in extreme examples of ultra-long and ultra-short cylinders this might not be perfectly true [regarding pressure over time] with the way the two shapes of spring expand on release...but it doesn't seem considerable in practice [with realistic cylinder shapes].
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J
Piston ID deffo matters, at least if you're a person who balances the internals. From tuning MB01, i can tell that it has way more torque against air pressure, and needs to be lighter than a comparable VSR setup.

1. Huh- so one of my main concerns is probably true- the data may not be useful at all for source volumes differing from that of what was used in the tests. Guess I may just have to commission a cheap super-long barrel and do my own cut-down test to find ideal ratios for my actual rifles...
2. How does it feel? Resistance slightly increases as you push the bolt forward?
3. What do you mean by high pressure lock? I was also going to dig around for education on piston weights, as I understand the general idea of why heavier is used for joule creep, but it's not something I've ever needed to concern myself with- what variables need to be taken into consideration when deciding the weight? Or is there basically no way to go too heavy?
Click to expand...
1: Deffo do your own tests. I always advocate this instead of taking tech information as gospel.

2: When you reach the end (last 2-3cm) of the forward stroke, it shifts the handle downwards. Imagine a stick in a groove with a 90degree soft bend.

3: Pressure lock = the pressure required to push the BB past the hopup bucking. If you disregard the backspin function of a hopup system, you can look at is as a valve for the BB, where you can decide how high pressure is needed before the BB is released (i've written a better post about this somewhere else).
With a short barrel and heavy piston, it is a super benefit to run a high pressure lock. The pressure lock allows pressure to build, and the heavy weight of the piston allows it to compress instead of bouncing on the air pressure.
Depending on how your hopup is set and how well it works, this can be a big difference. If you run a 300mm barrel + heavy piston, you basicly need to run NOT rhop patch to get max energy.
Compared to light (ish) piston, long barrel and rhop, it's like two completely different approaches to transferring energy. Short barrel you let the pressure build up as much as you can, long barrel you want as little resistance as possible so you can retain piston speed and accelerate over a long distance.

If you want to try something fun, build a VSR with 300mm barrel, 100gr piston, stock bucking design and .48 or even .87...the muzzle crack is UNREAL. With high power spring ofc.

This is why i want a hopup system that can seperate pressure lock and backspin friction =)
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wyz2285
I can try to find it, but it was years ago when I was into airguns; If you search airgun forums you will find a lot info regarding spring powered vs HPA. If I remember correctly typical AEG produces peak pressure around 300 PSI; You can also reverse calculate it, say you have a 1,5J gun at a given cylinder volume, resume around 60% energy transfer then you have a required pressure for the given system.

It's just a way of speak meaning you can't accelerate a bb indefinitely with air volume and barrel length. But I do know a couple individuals who managed to accelerate airsoft bbs to insane speeds (>mach 3)

Pressure = force/area, per example PSI means pound per square inch. Therefor smaller ID = smaller area = less force required to reach the same pressure
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MagicMarker
Jeppe said:
[...]
Click to expand...
The consideration of pressure lock just seems...like a ridiculous undertaking to take into account and build around. Is it that important? I'll have to dive your profile for more on this...
Also, are you aware of any sources for getting myself acquainted with how cylinder diameter, cylinder length, and piston weight effect the system? The HTI has me all hot and bothered but I'm such a noob to the cylinder world that I don't even know if I have a significant performance-related reason to pursue building a new rifle- especially considering the notion of pressure lock actually quells my concerns about HPA systems' inherent shortcoming I mentioned.

wyz2285 said:
[...]
[...]
Pressure = force/area, per example PSI means pound per square inch. Therefor smaller ID = smaller area = less force required to reach the same pressure
Click to expand...
Really interesting, huh.
Mach 3...I really want to see that in person >:D
But that math would be assuming the smaller ID cylinder had the same spring as the larger, no? Even simpler, the force/area at the identically-wide nozzles of the two systems should be equal if both have identical volume and force behind them, right?
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J
The consideration of pressure lock just seems...like a ridiculous undertaking to take into account and build around. Is it that important? I'll have to dive your profile for more on this...
Also, are you aware of any sources for getting myself acquainted with how cylinder diameter, cylinder length, and piston weight effect the system? The HTI has me all hot and bothered but I'm such a noob to the cylinder world that I don't even know if I have a significant performance-related reason to pursue building a new rifle- especially considering the notion of pressure lock actually quells my concerns about HPA systems' inherent shortcoming I mentioned.
Click to expand...
I think it's important enough to not ignore. Sometimes it has a big influence.

With a 95gr piston / 300mm barrel i was still gaining energy from increasing hopup even when overhopping a .50. Like, straight up in the air after 20 meters overhopping. And at lower hopup settings it was not very stable.

I don't know where to read more about it. Most of the stuff centered around heavy pistons now seems to be silly weights mainly for the purpose of joule creep, wether they want to admit it or not.

I seem to be the only one around that weights pistons/rifles for a balance with other parts.

It is very common in the airgun world though.
They also use nozzle ID (transferport) as an airbrake. Too wide, the piston slams. Too narrow, the piston bounces on pressure.
They are also big on compressing every tiny bit of air out of the cylinder. Not for a matter of total volume, but rather because the final air left in the cylinder at end of travel contains a lot of energy (it's compressed) and trapping it inside the cylinder means a lot.

I believe we have not yet made the most optimal pistonhead/cylinderhead assemblies we can. Vent holes etc in pistons is not really good for this...you want the seal to be far forward.

Interestingly, the SRS/HTI cylinderhead design is really well done in terms of squeezing all the air out and still having a cup design.

UK company "airgun tech" has some super interesting blogs on performance tuning. Different energies, but not that far off.

One of my biggest pet peeves with airsoft is how most springs get overcompressed and worn out. Double bearing in AEG will do this on heavier springs, as will most VSR pistons when fully cocked. VSR springs are bare for this as well. Almost all VSR springs, especially with short inner tube pistons, will start to bend and lose a bit of power.

Except all the springs that i cut down, ie. remove coils. They stay perfectly shaped and don't lose power.

Same thing for AEG springs in shortstroked guns. They are mint after 300K shots.

For the HTI, the increased piston surface means it will have high air pressure/flow at low piston speed.
I asked them about this, and they said the 1,7J version of the HTI was working fine and stable even with 100gr piston.

The short answer is: Yes the HTI will outperform any (spring) VSR and probably be more precise. No contest.
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J
On a side note, i don't think spring and HPA math is comparable at all.
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MagicMarker
Jeppe said:
I seem to be the only one around that weights pistons/rifles for a balance with other parts.
[...]
They are also big on compressing every tiny bit of air out of the cylinder. Not for a matter of total volume, but rather because the final air left in the cylinder at end of travel contains a lot of energy (it's compressed) and trapping it inside the cylinder means a lot.
[...]
The short answer is: Yes the HTI will outperform any (spring) VSR and probably be more precise. No contest.
Click to expand...
When you say 'stable', are you referring to the consistency of power readings? The lack of pressure lock causing the BB to slip free less consistently?
1. Oh wow, you mean physically, for the overall feel of the weight distribution? Yeah that's a first for me! Though I have to say, I love the difference in weight going from my Tanakat to my VSR; the VSR is so light in general, having a large majority of any weight in the stock where the tank is- it feels much better than forward weight to me.
2. It means a lot in terms of wear on the mechanism, or in muzzle velocity? Both I'd imagine, I suppose.
3. So what exactly makes you so confident the HTI is going to be so great? I want the long answer :p I see you outright note efficiency in squeezing out cylinder air with a good design, and the obvious benefit of reduced wear/vibration/sound with the up-scaling- but what else? You mentioned the high air pressure/flow at low piston speed- is this good for stability as I clarified the definition? If not, can you explain why that would be beneficial? This comes as a bit of a surprise to me, because when considering the curve of pressure over time at the nozzle, it seems to me that an increase in cylinder volume would be getting more similar to an HPA system's curve- HPA systems may not reach as high a pressure peak, but aside from that, this notion makes me wonder why so few chairsoft sniper nerds don't dedicate themselves as much to HPA systems. It's not like consistency is difficult to achieve- you just need two inline regulators to get +/-0FPS. I suppose it's at least partially due to less control over individual variables governing the pressure curve..?

Jeppe said:
On a side note, i don't think spring and HPA math is comparable at all.
Click to expand...
Well, surely they're different in the way the energy is transferred, but I'd imagine the sole concept of volume tuning isn't wildly different if we're operating on the assumption decompression of the source occurs before the BB breaches the muzzle (hmmm...are we though :nuts:).

Also the numbers on gas rifle source volumes:
M40A1 @ 3.41J: 89cc
Bolt (red spring, 3 shims; 180PSI) @ 2.84J: 72cc [hm, looks familiar Mr. HTI...]
Yes, much larger than a VSR of 36cc, but works out quite well for having a normal-looking rifle length, when most people tuning volume end up with stubby things :p
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