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Good reading for accuracy vs fps. Info found on evike forum
The contents of this post are from evike and do not in any way reflect the opinions of the poster.
So I've finally reached that point to where I am annoyed enough of explaining the reason why the longer and tighter is not always better.
The barrel, most noobs and a suprising amount of not so noobs are under the tighter and longer is king type spell, well sad to say its total bull ****! It has long been accepted in the spring powered bolt action world that anything over 509mm is pointless and actually causes the rifle to be less accurate, and that the VSR performs best with a barrel between 430mm and 480mm. It is also considered widely that an AEGs can be accurate with a barrel as short as 363mm.
While we are considering barrels its also worth thinking about the bore size, most people believe the tighter it is the more accurate it is, if this is so why are most VSR users moving to 6.05mm bore barrels as they are more accurate than a 6.01? And why are some major Japanese companies starting to advertise 6.08mm barrels as their accuracy barrels?
- "The Holy Grail of DMR build".
The Bore
The sweet spot for TBB is somewhere between 6.03 and 6.05. Although, barrels that do not follow the sweet spot can also be very accurate based on the tolerances of the barrel. By far the quality and smoothness of the bore and crown out weigh the tightness of the bore.
For example, I could have a 450mm 6.03 JBU which has a lower quality bore, than a PDI 6.01 450mm, which has a higher bore quality. Even though the JBU is in the "sweet" spot, the PDI would out perform the JBU due to the fact that the quality of the bore is much better.
Lets say you had a Prometheus 6.03 and a PDI 6.01, both of the same length. Contrary to popular belief, they would both perform pretty much the same, since the quality of the bores are both on par, there might be some slight variance, but overall they would yield the same groupings and range. Although theoretically the Prometheus 6.03 should out range the PDI. Even through PDIs own admission they have admitted that their 6.01 TBB was designed for power and their new 6.05 TBB was designed for "carry".
That being said, there are only a few tested and reliable brands that have the quality bore we are all looking for to get the best accuracy.
These would be, PDI, Prometheus, Madbull, Deep Fire, Stock TM, and Systema. There may be more quality barrel brands out there that I forgot, But these are the nice smooth Bore TBB.
There is also the Tanio Koba Twist barrels. The most widely accepted theory as to why they work is because they leave a cushion of air around the BB while it is in the barrel causing it to not touch or rub on the sides of the barrel, keeping its flight path and straight as possible. However these barrels are supposed to yield the optimum results on an 1 joule set up, since the groves cut in the barrel are set for only 1 joule, any more would disrupt the air flow and cause turbulence within the barrel, and due to the groves, it would cause inaccuracy. However there are some that claim the barrel works good on guns that shoot up to 500 FPS. I have tested these barrels, and I will attest to their great range and groupings with a 1 joule gun.
BB Dynamics Within a Barrel
Now I will try to explain the Dynamics of a BB as best as I understand the way it works.
The reason behind the sweet spot of the barrel (tightness and length) is due to how the BB stabilizes when it is inside the barrel.
As you fire your gun, the air sends the BB through the bucking giving it hop. After it passes the bucking where the hop is given. The BB shoots up and hits the roof of your barrel, This is cause the BB to bounce around your barrel until it stabilizes and starts to roll along the top of your barrel due to the hop-up.
The reason for the sweet spot in tightness is because the wider the bore, the less the BB will bounce around. Each time the BB bounces, it loses some of its back spin, but it has a chance to hit a rough spot or uneven patch within the barrel, if it hits this slight "rough" spot it will throw off the bounce of the BB and cause it to destabilize, changing the bounce and the backspin given to the BB.
This also leads to the reason for a sweet spot in length. The sweet spot in the length is about the point where the BB will stabilize and start to roll along the top of the barrel. The reason why the longer is not always better is because once the BB stabilizes, no matter how long its rolling on the top of the barrel it will not get any more accurate. In fact, it can reduce your over all range since rolling along the top will rob the BB of some of its back spin causing it to fall more quickly. Furthermore, the longer the BB rolls along the top, the bigger the chance of it hitting a rough spot causing it to destabilize.
BB Quality
Again with the whole wanting a smooth bore to fire your BBs though. The whole reason we have so many different barrel manufactures out that have the quality bores we are looking for in a rifle. You also have to consider the BB quality. The quality of the barrels are already really high, that is why out of many different companies ranging from different prices, you get similar results. However, the quality of BBs are not universal. There are many high quality and low quality BBs out there. The reason for this is that BB quality is far behind that of the barrel. This is because of the way BBs are manufactured. The smoother the BB the better it will be as I explained earlier. You also need to take into account air bubbles. Ever wonder why the bioval BBBMAX .27g bbs were so good? Its because they had 0 air bubbles and the material they used to make it left a VERY smooth and uniform BB surface. The only reason no one uses them is because the material (silica) is pretty hard and can shatter our conventional eye protection. That being said the reason behind air bubbles when manufactures make BBs is because of the processes in how the BB cools, that and another reason is because it keeps the weight down for lower gram bbs. By far the only BB manufacturer that I know has 0 air bubbles and a smooth surface is Golden Ball, I have yet to test and crack some SGM due to their price. But the higher quality BBs from my experience are : Golden Ball, Bioshot, Bioval, AE and some of the heavier weight madbull BBs (since they are the only cheap brand of heavy weight BBs). There may be others, but also keep in mind, you have to wash the KSC and Golden Ball BBs, they will get your barrel dirty really quickly due to the polishing process they use.
So how do we get better range and groupings? :o
The answer is from getting as good of an air seal as possible. This involves many DIY stuff to boost up compression through out your gun. This can be done by shaving down some parts, to swapping out or installing o-rings on parts to improve compression. A gun with good compression and a nice barrel will out range those that shoot hotter (EX: Tokyo Marui and JG). Also volume balance will help increase your FPS as well as range and groupings.
Well, that's all I have for now. If you read the whole post, I congratulate you for reading my rambling on barrels, accuracy, and theories of BB dynamics. :mrgreen:
So I've finally reached that point to where I am annoyed enough of explaining the reason why the longer and tighter is not always better.
The barrel, most noobs and a suprising amount of not so noobs are under the tighter and longer is king type spell, well sad to say its total bull ****! It has long been accepted in the spring powered bolt action world that anything over 509mm is pointless and actually causes the rifle to be less accurate, and that the VSR performs best with a barrel between 430mm and 480mm. It is also considered widely that an AEGs can be accurate with a barrel as short as 363mm.
While we are considering barrels its also worth thinking about the bore size, most people believe the tighter it is the more accurate it is, if this is so why are most VSR users moving to 6.05mm bore barrels as they are more accurate than a 6.01? And why are some major Japanese companies starting to advertise 6.08mm barrels as their accuracy barrels?
- "The Holy Grail of DMR build".
The Bore
The sweet spot for TBB is somewhere between 6.03 and 6.05. Although, barrels that do not follow the sweet spot can also be very accurate based on the tolerances of the barrel. By far the quality and smoothness of the bore and crown out weigh the tightness of the bore.
For example, I could have a 450mm 6.03 JBU which has a lower quality bore, than a PDI 6.01 450mm, which has a higher bore quality. Even though the JBU is in the "sweet" spot, the PDI would out perform the JBU due to the fact that the quality of the bore is much better.
Lets say you had a Prometheus 6.03 and a PDI 6.01, both of the same length. Contrary to popular belief, they would both perform pretty much the same, since the quality of the bores are both on par, there might be some slight variance, but overall they would yield the same groupings and range. Although theoretically the Prometheus 6.03 should out range the PDI. Even through PDIs own admission they have admitted that their 6.01 TBB was designed for power and their new 6.05 TBB was designed for "carry".
That being said, there are only a few tested and reliable brands that have the quality bore we are all looking for to get the best accuracy.
These would be, PDI, Prometheus, Madbull, Deep Fire, Stock TM, and Systema. There may be more quality barrel brands out there that I forgot, But these are the nice smooth Bore TBB.
There is also the Tanio Koba Twist barrels. The most widely accepted theory as to why they work is because they leave a cushion of air around the BB while it is in the barrel causing it to not touch or rub on the sides of the barrel, keeping its flight path and straight as possible. However these barrels are supposed to yield the optimum results on an 1 joule set up, since the groves cut in the barrel are set for only 1 joule, any more would disrupt the air flow and cause turbulence within the barrel, and due to the groves, it would cause inaccuracy. However there are some that claim the barrel works good on guns that shoot up to 500 FPS. I have tested these barrels, and I will attest to their great range and groupings with a 1 joule gun.
BB Dynamics Within a Barrel
Now I will try to explain the Dynamics of a BB as best as I understand the way it works.
The reason behind the sweet spot of the barrel (tightness and length) is due to how the BB stabilizes when it is inside the barrel.
As you fire your gun, the air sends the BB through the bucking giving it hop. After it passes the bucking where the hop is given. The BB shoots up and hits the roof of your barrel, This is cause the BB to bounce around your barrel until it stabilizes and starts to roll along the top of your barrel due to the hop-up.
The reason for the sweet spot in tightness is because the wider the bore, the less the BB will bounce around. Each time the BB bounces, it loses some of its back spin, but it has a chance to hit a rough spot or uneven patch within the barrel, if it hits this slight "rough" spot it will throw off the bounce of the BB and cause it to destabilize, changing the bounce and the backspin given to the BB.
This also leads to the reason for a sweet spot in length. The sweet spot in the length is about the point where the BB will stabilize and start to roll along the top of the barrel. The reason why the longer is not always better is because once the BB stabilizes, no matter how long its rolling on the top of the barrel it will not get any more accurate. In fact, it can reduce your over all range since rolling along the top will rob the BB of some of its back spin causing it to fall more quickly. Furthermore, the longer the BB rolls along the top, the bigger the chance of it hitting a rough spot causing it to destabilize.
BB Quality
Again with the whole wanting a smooth bore to fire your BBs though. The whole reason we have so many different barrel manufactures out that have the quality bores we are looking for in a rifle. You also have to consider the BB quality. The quality of the barrels are already really high, that is why out of many different companies ranging from different prices, you get similar results. However, the quality of BBs are not universal. There are many high quality and low quality BBs out there. The reason for this is that BB quality is far behind that of the barrel. This is because of the way BBs are manufactured. The smoother the BB the better it will be as I explained earlier. You also need to take into account air bubbles. Ever wonder why the bioval BBBMAX .27g bbs were so good? Its because they had 0 air bubbles and the material they used to make it left a VERY smooth and uniform BB surface. The only reason no one uses them is because the material (silica) is pretty hard and can shatter our conventional eye protection. That being said the reason behind air bubbles when manufactures make BBs is because of the processes in how the BB cools, that and another reason is because it keeps the weight down for lower gram bbs. By far the only BB manufacturer that I know has 0 air bubbles and a smooth surface is Golden Ball, I have yet to test and crack some SGM due to their price. But the higher quality BBs from my experience are : Golden Ball, Bioshot, Bioval, AE and some of the heavier weight madbull BBs (since they are the only cheap brand of heavy weight BBs). There may be others, but also keep in mind, you have to wash the KSC and Golden Ball BBs, they will get your barrel dirty really quickly due to the polishing process they use.
So how do we get better range and groupings? :o
The answer is from getting as good of an air seal as possible. This involves many DIY stuff to boost up compression through out your gun. This can be done by shaving down some parts, to swapping out or installing o-rings on parts to improve compression. A gun with good compression and a nice barrel will out range those that shoot hotter (EX: Tokyo Marui and JG). Also volume balance will help increase your FPS as well as range and groupings.
Well, that's all I have for now. If you read the whole post, I congratulate you for reading my rambling on barrels, accuracy, and theories of BB dynamics. :mrgreen:
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