Front Bolt and Powertube Test
How the Tippmann A5 Works:
Before we begin, I would suggest you study the animation and read the description below:
Here is a synopsis of how the Tippmann A5 internals work. Gas comes in through the hose and into the tombstone (dark green). The tombstone is inserted into the powertube (orange outline), which holds the valve (grey), and into the valve itself. It sits up against the valve and feeds directly into it through the middle. The user pulls the trigger (solid orange), which in one way or another trips a sear (pink), and releases the hammer (light green). The drive spring pushes the hammer forward towards the valve. The front bolt (red) is connected to the hammer via a linkage arm and allows them to move in unison. As the hammer moves forward, the front bolt pushes the ball through the barrel adapter and into the barrel. At the end of the hammer’s travel, it slides into the powertube, making a seal with its o-ring, and hits the valve pin. The pin releases the gas, which fills up the cavity where you can see the pin. The air is directed directly into the Cyclone/RT port as well as through channels outside of the valve (but still inside the powertube). The channels route the air around the tombstone and in front of it, where it converges again at the powertube extension. There it travels through the extension, through the front bolt, and out the barrel. At the same time, the escaping gas is also pushing the hammer backwards until the hammer pops out of the powertube where the gas then escapes in all directions and out of the gun. The hammer’s inertia finishes the action of the gun and returns the bolt back to its original position.
Reasons for Test:
I felt the original front bolt comparison thread had several major flaws in it that I will try to address. The comparison that I refer to can be found below. Please read it before continuing this article.
Scientific side by side comparison of leading aftermarket front bolts for the A-5!
Firstly, I think that an accuracy test was not the way to go. Most of a gun’s accuracy comes from the barrel and its bore relationship to the paintball. I’m avoiding using paint-to-barrel-match because there is current testing in this theory that questions what is the perfect bore relationship and is inconclusive at the moment. The only affect that a front bolt can have on a ball’s accuracy is in the vertical dimension due to velocity deviations.
The original comparison also used the Flatline barrel, which doesn’t have the best accuracy. IMO, that is a poor starting point to base an accuracy test on. Especially since the ball is changing spin directions inside the barrel. Also, the rough texture of the inside walls of the barrel not only may cause fluctuations in accuracy but it also prevents any kind of seal for the ball, which may allow gas to blow past. There are too many variables associated with the Flatline barrel for a test such as this.
The data did not show any shot velocities or other statistics; there were no consistency results or efficiency results. Consistency refers to the ability to repeat something reliability and with little to no change. A bolt with good consistency will have velocities that fluctuate very little and bad consistency will have a lot changes. The changing of velocity will make a ball travel farther/shorter, which also translates to higher/lower vertical groupings due to gravity affecting its trajectory. The front bolt should not affect a ball’s horizontal movement. I reserve that for the barrel.
The front bolt also controls a gun’s efficiency by controlling the release of the gas. Depending on the design, it’s possible that gas is escaping in other ways and isn’t going solely through the barrel. This loss of pressure and volume will affect a ball’s velocity and/or consistency. A bolt with bad efficiency would require more volume/pressure to make a ball travel the same speed as a bolt with good efficiency. That means less shots per tank simply through design. The original test never considered this.
I’m going to refer back to the lack of statistics. Without having any numbers to look at, we can’t come up with any confidence intervals (an interval estimate that contains the true mean velocity within a certain percentage of confidence) or consequently if the differences in the results shown are significant or not. We also can’t analyze the data further on our own and come up with a result that may not have originally been conceived.
Lastly, only 1 powertube was used in the test. Powertubes also have many variables associated with them and each one could affect a single bolt’s performance. Factors such as material, extension diameter, extension shape, front velocity adjuster (FVA), Cyclone/RT ports, etc. What may work well with one powertube may have a different result with another powertube.
That’s where this test comes in. Not only were the front bolts looked at but powertubes were as well to give a more comprehensive look at the bivariate relationship occurring.
Here is the list of factors that were considered for the test:
2.FVA/Cyclone vs. no-FVA/Cyclone vs. no-FVA/no-Cyclone
3.Powertube extension diameter
4.Powertube extension shape
5.Powertube valve diameter
7.Combination effect (ex – New Designz, Rufus Dawg, etc)
8.Front bolt length
9.Front bolt inner o-ring
10.Front bolt inner o-ring distance from base
11.Front bolt outer o-ring
12.Front bolt outer o-ring distance from tip
13.Front bolt linkage arm hole distance from tip
14.Front bolt shape
15.Front bolt material
There are many variables associated with this test and the best way is to test all of the bolts on all of the powertubes (when possible). Just for good measure, the powertubes were also measured for the sound level differences to give actual data to prove whether or not metal powertubes are louder than plastic ones.
Here is the setup I have:
1.Newer style A5 receivers w/ Cyclone/RT ports and polished internals
2.Metadyne folding stock
3.Maddmann blue spring
4.Freak back and 12” freak front using the Reball insert
7.AKA 2-Liter Plus Dual regulator w/ HP spring and 7/8” extender cap
8.Braided stainless steel hose
9.CP direct mount on/off ASA
10.32 degrees remote line w/ Lapco slide check
11.68/4500 Pure Energy HPA tank
I took several steps to help isolate variables that could potentially skew the data. The first was to eliminate the Cyclone feed. The Cyclone takes air from the valve to cycle the paddles and feed the gun. Since there are so many mods and configurations for Cyclones, the Cyclone was a liability to the test and needed to be eliminated. I plugged both the Cyclone and RT ports in addition to putting packaging tape over the Cyclone ports on any powertube that had such a port (thanks for the tip Scoreshot). The Cyclone was used but had to be cycled manually since the Cyclone port was sealed and was unable to turn on its own.
All bolts and internals were properly oiled and then dry fired to eliminate excess oil. The regulator and all internals were oiled prior to each powertube test. The front bolt section was wiped with a paper towel to only allow a minimal amount of oil, just like if being used with paintballs. Excess oil can cause accuracy issues. I also made sure that powertubes that had an FVA were set flush with the inside of the powertube to help control its influence as well. This would allow a fair comparison to powertubes that don’t have an FVA. Those that did have an FVA but did not have a Teflon set screw had Teflon tape added to the FVA to prevent accidental unscrewing during the test. All powertubes used the same X7 valve.
As you may have noticed, I did not use paintballs for this test. Instead, I opted for Reballs. Not only did it make it more convenient but it also made it more consistent and reliable than paintballs. Paintballs can fluctuate in size, shape, run the risk ball breaks, and can only be used once. Reballs are reusable (my wallet thanks me) and have a more consistent shape. I used the Reball insert because through my insert test (link here), I found that it gave the best combination for consistency and efficiency.
Here is data comparing the roundness and weights of Reballs to paintballs:
Ball Density and Roundness Test
I conducted the test with one powertube for each set and only changed the front bolts. To change the front bolts, I disassembled the receiver halves rather than adjust the FVA and field strip it. Rather than adjusting pressure for each bolt, I set the gun’s velocity as close as possible to 280 fps for the stock powertube and stock bolt and kept it there throughout the test. That will show the efficiency of the bolts based on the stock setup. Those with better efficiency will give a faster velocity, which would require a person to turn down their pressure to achieve the same velocity. That would yield more shots per tank. Those with worse velocity would have to either turn up their pressure or achieve more volume through other methods. It will also show how other powertubes compare to the stock powertube.
I am using the F1 Shooting Chrony chronograph. It is accurate to within 0.5% and is compatible with Reballs, unlike most Doppler chronographs. All weights were obtained with a Palmscale 7.0 scale, which is accurate down to 0.01 g. All lengths were measured with an Oshlun digital caliper, which is accurate to 0.001”. I measured sound with a Radio Shack digital sound level meter. All shooting was done indoors where wind and temperature were not a factor.
For the sound test, I placed the sound level meter about 10 feet away and aimed it towards the ceiling. The gun was placed at shoulder level and was aimed at 90 degrees from the SLM towards a wall. Since I had to leave the Cyclone/RT ports closed, the Cyclone wouldn’t function for this test. I had to dry fire the gun during the test because I couldn’t cycle the loader fast enough to feed balls to it. I placed the E-grip on full auto at 15 bps and set the SLM to measure for 6 seconds. The SLM was set to Slow response and C weighting.
Here are pics of my setup:
Remote air and line holder
Work station with parts, tools, and supplies
Front bolts and Powertubes
Front Bolts from left to right:
5.Real Action Paintball (RAP4) Venturi Star
Powertubes from left to right:
3.JCS Red Hot
5.JCS Silver E-Tube
How to Read the Data and Understand it:
Here is the data: Powertube and Front Bolt Test
At first glance, the data is quite massive and overwhelming. The best thing to do is take it one part at a time. I will do my best to break it down to explain the organization, statistical terminology, and graphs.
PT stands for powertube and FB stands for front bolt. All of the raw data is collected in tabs marked with PT in the name All of the raw data is collected in tabs marked with PT in the name. The Every possible combination was recorded in those tabs. All of the other tabs and graphs are derived from those first sets. It’s the same data just organized in a different way. Since this is a dual variable test, it needed to be presented in two ways to analyze it best. Tabs with PT in the name use powertubes as the constant and the front bolt is the variable that changes. Tabs with FB use front bolts as the constant and the powertube is changed. The PT tabs are useful to compare front bolts to one another. If you keep the powertube the same, the only thing that is changed in the gun is the front bolt. The opposite is true for the FB tabs; they are useful to compare powertubes. Each part has its own set of graphs. This also allows someone with an existing part to see what corresponding part would benefit them the most.
Rows 1 through 50 are the shot numbers recorded in feet per second (fps). The Rufus Dawg Wicked bolt usually has an N/A (not applicable) for its data because it is incompatible with all other powertubes except the Rufus Dawg powertube. The data is analyzed below the raw data and the specifications for the part are below the statistics.
Let’s talk about a few statistics definitions so we can comprehend what we’re looking at. Range is the maximum amount of velocity change that occurred. If you take the highest velocity and subtract the lowest velocity, you have the maximum difference, which is the Range. It is good to know because it shows the maximum potential fluctuation that can occur. It does not imply that is what most of the shot fluctuations will be.
The Mean is the average velocity. You can obtain it by adding up all the velocities and dividing it by the number of shots. It will give you the middle point of the velocities and what you will expect to see most of your shots to be the closest to.
Variance is another statistic but is usually used to obtain the standard deviation (SD). The SD is where we want to look at for consistency. The SD isn’t simply dividing the range by 2. It’s the square root of the variance but to obtain the variance is a bit tricky and it isn’t necessary to explain how to obtain it for this test; only what it means is important. It’s expressed in terms of the unit being measured, or in our case fps. The SD shows how much it fluctuates from the mean. Generally speaking, if the sampled distribution is normal, then 1 standard deviation should encompass about 68% of all shots. You can go 2,3, or more standard deviations to cover more of the population but most of your shots will lie in only 1 standard deviation. We can thank the wonderful Bell curve for that. The SD is what we’ll be looking at for consistency as it shows how much the velocity will usually fluctuate.
As you may have noticed, the range is not always the same as the standard deviation. That is because outliers can affect the range but they have a lesser impact on the standard deviation. That is why standard deviation is a better measurement for central tendency.
Confidence intervals are a quality measure. The most common CI used is the 95% interval. It tells us that 95% of the confidence intervals we have obtained through repeated sampling would enclose the true value of the mean. In other words, if we did more samples, we would most likely find the true value of the mean within the interval. It is not guaranteed though. There are still likelihoods that the mean captured is in the 5% range. So never take values like this as an absolute certainty. Below the 95% CI are the high and low values of the CI so that you get an idea of what I meant. If you compare it to the mean value, the CI value is +/- of the mean and that gives us the high and low values. The larger the interval usually implies that there is more fluctuation occurring and it is less consistent.
After the FB section are a few analytical tabs. The Specs Comparison tab compares different dimensions of the front bolts and powertubes to look for trends or a correlation to their respective performances. I did not weigh the powertubes because it is irrelevant as they don’t move inside the gun. Only the front bolts were weighed because it is a moving part and is directly linked to the hammer, which it’s weight could affect performance.
The Mean Velocity vs Standard Deviation tab is a collection of mean velocity and standard deviation graphs put into one graph. I used the original numbers for the standard deviations and exaggerated them so that they are easier to view and so that they would fit on the same graph as the mean velocities. I simply squared the SD and added 175 so that differences would become more apparent. It makes it easier to compare graphs and see what is going on by putting them all on a single graph. On the bottom of the page are Standard Deviation Range graphs. I took all of the SD’s and found the range for all combinations. I was curious if the standard deviations had a central tendency of their own. Those with lower values were more likely to fluctuate less on the standard deviation and to hold their value better. This would show more reliability in the numbers found.
Lastly is the Best Combo for Efficiency page. This shows the best combination per powertube and compares their performances based solely on efficiency. It does not take into consideration consistency and is not a hands down overall winner. I did not include a similar ranking for consistency because I did not feel there was enough evidence to confidently declare any kind of winner. Perhaps future testing will show something later on that will reliably show consistency.
The Superfly, NDZ, and Rufus Dawg front bolts needed to have the linkage arm holes drilled out. They were too small for the linkage arm to fit. The Superfly had to be drilled straight through to the center extension hole.
The NDZ bolt was EXTREMELY tight on the stock powertube. The gun almost wouldn’t cycle because of it. It eventually broke loose without any damage to any parts.
The Rufus Dawg front bolt can only be used on the Rufus Dawg powertube because of the “guides” hitting the end of the powertube extensions. The Rufus Dawg PT has slots cut out while the other PT’s do not. Thus, the gun will only cock backwards until the extension hits the guides.
The Trinity powertube was extremely tight. Getting the valve into the powertube was difficult. The action of the marker felt like it was sticking due to the hammer being too tight inside of it. I left the powertube as is for the test rather than sand it down to make it work as that would have jeopardized the results by modifying it.
The Trinity front bolt did not fit the trend of consistency for the powertubes and am unsure why. Even after retesting, it's standard deviation was exactly the same and way off of the expected area for it to be in. This may cause the consistency data to be skewed.
All o-ring measurements were taken when installed on the part. They were not taken separately. The hammer’s o-ring measured 0.932”. The valve’s o-ring measured 0.949”.
1. The old assumption that less airflow disruptions are better is inconclusive. I did not find that eliminating the FVA or Cyclone/RT ports gave better performance. As you can see, the stock powertube actually gave better efficiency across the board than those without the FVA. The consistency is inconclusive because it peforms both better and worse for certain powertubes. So eliminating the FVA or Cyclone/RT ports is not a given for better performance.
2. Front bolts with inner o-rings give better efficiency than those without it. As you can see, every bolt has a higher mean velocity than those without inner o-rings with the exception of the Rufus Dawg powertube. Since there is a gap between the front bolt and the other powertubes, air has the potential to escape out through it. By putting an inner o-ring, as you can see, it gives better efficiency. This is particularly evident on the New Designz powertube. If you look at the mean velocities, those without inner o-rings drop off quite sharply because of the tapered powertube extension. The Rufus Dawg powertube is the exception because of the “guides.” Most of the bolts are shorter and do not cover up the guides fully, allowing air to vent out behind the bolt. The Orange and Rufus Dawg bolts do cover up the guides thanks to their extra length behind the armature pin hole. The Orange bolt goes even further by sealing it off with the inner o-ring. That is why some bolts with inner o-rings perform similarly to those that don’t have them on this powertube.
3. Longer front bolts do not necessarily give better efficiency. At first glances, this could be deceiving but we need to look at the data a little deeper to understand why this is not the case. If you compare the bolts from the armature pin hole to the tip of the front bolt, they are nearly the same. There is little significant difference between bolts. That means the extra length that we’re seeing is at the base end of the bolt and not the breech end. We can’t compare the Rufus Dawg front bolt mean velocity to the others simply because of the design of the bolt. It is only compatible with the Rufus Dawg powertube, which has guides. For normal powertube designs, nothing suggests that the extra length provides any benefit.
4. To get better efficiency, front bolts must seal off the barrel adapter better. As you can see with the Starfire and RAP4 bolts, there is not a good seal being made and more gas is escaping around the bolt.
5. My hypothesis about larger outer o-rings is that they will yield better efficiency. Taking the inner o-ring data into consideration along with the lack of a proper seal of the Starfire and RAP4 bolts, one can only assume that the same is true for outer o-rings as well. And if we look at the Outer O-ring Diameter Graph, the first 3 do not have an inner o-ring but the outer o-ring does penetrate into the barrel adapter. The DOP has a higher mean velocity because it has a larger outer o-ring. The Superfly, Orange, and NDZ, however, do not have similar trends with mean velocity and I suppose it is because of the inner o-ring diameter. The NDZ bolt has the smallest inner o-ring, which puts more friction on some powertube extensions, which slows down the action of the hammer and strikes the valve slower and with less force. That leads to a smaller open valve time and consequently less volume. That would equate to a lower velocity. The Superfly inner o-ring, however is larger but its outer o-ring is much smaller. So it’s possible that is why the Superfly mean velocity is lower than the NDZ bolt. If you consider the situation of the Rufus Dawg powertube (escaping gases), then it is entirely possible that escaping gases will yield a lower velocity. That’s why I think larger o-rings will give better efficiency.
6. Plastic powertubes give better efficiency than metal powertubes. I believe this is due to lower friction. There is no trend relating the hammer or valve o-ring diameters to the powertube inner diameter and the powertube’s efficiency with the exception of the Trinity powertube. That was physically apparent but not on any other powertube. If you look at the Outer Diameter (tip) graph, there is a very similar trend occurring to the powertube’s efficiency but it is not identical. For example, the E-tube should perform only slightly less efficient than the Stock tube based on the outer diameter but, instead, it is quite a bit more inefficient. The reason the Rufus Dawg powertube did worse than the Stock powertube is because of the “guide rails” at the end of the extension. Near the end of the action, the “guides” get exposed and gas is able to leak out. My hypothesis is that the metal powertubes have more friction than the plastic tubes. Not all of the metal powertubes have a very smooth finish on the outside of the extensions. It may also be possible that the inner o-rings have a lower friction coefficient against the plastic than they do against the metal. Another possibility is that the hammer’s o-ring is better able to slide because of the plastic and that leads to better efficiency. Whatever the explanation is, the data is showing that plastic powertubes provide better efficiency than metal powertubes.
7. The data is inconclusive as far as consistency for front bolts. There is no trend that I was able to find in any variation of graphs that I produced that were able to directly link the standard deviations. It is my assumption that consistency is related to other factors beyond the powertube and front bolt. However that does not mean that a trend does not exist. It simply means that whatever is causing it to fluctuate is masking what the true trend is.
*On a side note, if you look at the Front Bolt Mean Velocity vs. Standard Deviation Graph, I have put all the standard deviation lines on one graph. It appears there may be a confidence interval for the standard deviations. It’s possible that some have a broader range of potential SD’s like the Trinity bolt whereas others have a smaller range like the Orange Howitzer bolt. It is possible that some bolts are better able to produce a more consistent consistency. This is just speculation though and is not my official conclusion. I just don’t feel that there is enough evidence that is significant enough to draw any conclusion about consistency.
8. All powertubes had the same sound level. Many people believed that metal powertubes provided a louder shot but the sound level showed exactly the same level for both weighted sound tests. It is entirely possible that conducting this test indoors is preventing a good reading but the weather at the time just isn't favorable yet for this test. What the sound level meter doesn’t show is pitch or any other sound attribute. It is possible that something else is different due to materials and our ears are more perceptible to those attributes. I just don’t have the equipment to test it at this time.
9. There are clear winners with regards to efficiency but application is very important. For example, if cracking powertubes is a problem, then you should compare the metal powertubes and see which performs the best. If you have a Cyclone or RT, then you need to exclude the Gold and E-tube powertubes. You have to consider the application for the part before you look at their performances and how they stack up.
10. This test makes no claims regarding ball breakage, accuracy, Cyclone performance, or durability of the powertubes (ie – cracking). I know I referred to accuracy in regards to consistency but since I have no data to back it up, I am making no claims about bolts or powertubes being more accurate than another.
I hope this test was insightful and comprehensive enough for people to reconsider previous notions they had when considering the internals of a Tippmann marker. Let this be a lesson that even though previous tests were conducted does not mean that it is the final word on performance, including this test. I hope that people are willing to do their own experiments to confirm or reject what data I or anyone else has collected. Repeatability through scientific testing warrants good results and conclusions. Please take it upon yourselves to think outside of the box and to take results with a grain of salt. I really hope that players will find this useful in making purchasing decisions on what to look for in a good performing part, and manufacturers will look at what factors makes a good part and will consider those factors in designing future parts.
Oh, and in case you were wondering what about 4,000 shots does to a floor mat at 15 ft, here you go.
Edited by Lord Odin, 29 June 2009 - 05:24 PM.