I look forward to playing with it more and getting my head around the features. Last edited by ajvanwyk on Sun Apr 26, am, edited 2 times in total. I understand the coal adjustments show the effect. It would be interesting if you could input chamber dimensions such as neck clearance and distance from the lands to see how it effects the pressure curve.
To get a the barrel time and curves I assume there has to be some input from sammi or the euro equivalent? I have simply had a crude play with the features but from what I have seen the speeds and nodes look pretty accurate.
As for making wildcats on the couch I will have another look to see if you can adjust the cases wall thickness and if it adjust to capacity. Have you seen if you can build a cartridge from scratch or can you only modify existing?
At this stage QL may be be more user friendly for cartridge design. I have not had a detailed look at GRT yet. But that may not be really necessary because both programs have minor limitations which I will explain in terms of tune. Generally speaking, the tune I see being developed with GRT is a nodal tune in its strictest sense where group size is meant to be correlating with a barrel length which is matched to a harmonic resonance according to the barrel time.
That is commonly assumed to be based on the time it takes for the speed of sound to travel through steel. I understand, this is the basis for an OBT optimal barrel time tune. Beware, different steels marginally change that time too. The concept is dependent on knowing a strict velocity at the muzzle. Lab Radar is the best tool to measure that we have at our disposal. Approximations had to be made for old chronographs in the past except for Magneto Speed. I like the way GRT facilitates this process.
But there is more to consider in the application of the programs. The former stands for optimal charge weight where the strategy is to find the best and most stable group. That is where three groups minimum, lie on a similar elevation and the middle one is chosen and refined with seating depth and neck tension. It may happen that a node lies in this section. The GRT program allows you to input shot position and so inspection of group relationship can be achieved.
This is good. However, OBT tune theory assumes it represents the best group. In reality this is not always the case when the subtle differences in harmonics are explored a little further. The OCW tune is a sound fallback tune, and most suitable when a nodal tune cannot be achieved and has the additional quality of stability if velocity changes. Not all barrel patterns are harmonic given that the illusory sine wave we plot from load development. It really represents a complex pattern of incident waves, stress waves and reflected waves sourced from ignition, the throat contact, rifling torque, the de-corking at the muzzle and an atmospheric node which lowers frequency.
It should not be viewed like a guitar string with two closed ends or a pipe with two open ends with the input of one incident wave. The barrel does not have the same harmonic pattern a solid length of steel either.
A push into the atmosphere occurs, and lowers frequencies. An analogy can be drawn to an organ pipe, where further additions to length need to be calculated beyond the simple harmonic length. So, I am not sure the correct theory truly matches the practice with the programs. They will be skewed a little if a forward of the muzzle tuner is used on a high-power rifle where calculations go beyond the 5th harmonic which a small bore shooter can reasonably get away with the use of such a tuner.
OCW tune is best represented by tune when the muzzle is in its straightest position, where you might see several adjacent groups in a load development group lying along a similar elevation as previously mentioned. It is not strictly, a long node. A harmonic node is strictly velocity dependent to achieve a resonant frequency even with an open-ended system with one input.
The OCW tune is more often utilized in stiff barrels with minimum muzzle lift; whereas a nodal tune by its nature takes advantage of an approximate harmonic frequency which can be found when a rhythmic sign wave is produced by incremental load development. This means there must be flex in the barrel. That means you apply the right tune type to what the barrel is doing. Assuming the sine wave is rhythmic, when we get down to the 6th harmonic value in the tune, the difference between an OCW tune becomes negligible because the frequencies are so fine and short.
OBT tunes can be beneficial in the range of the 3rd harmonic to the 5th harmonic frequencies which are even divisions in theory, of the fundamental frequency initiated in barrel lift. There is correlation but not necessarily causation. Of course, compensation tunes do occur where the bullet exits the muzzle due to real time differences in barrel times of shots in a group.
So, you have to ask yourself does a tight cluster really represent a harmonic node. In many cases a tight cluster is said to be a node in shooter speak.
In physics, the tops and bottoms of the sine wave are really the anti-nodes. So our terminology is blurred and this adds to problems of communication. You may change values in QL manually too when the chronograph figures suggest the inputs need adjusting when the results are different from the software prediction.
The usual thing is to adjust the burn rate of the powder or fudge the weight. Seating depth pressure examination may be achieved by adjusting the initiation pressure. That becomes a huge cost saving. That's the important bit. The rest is merely fine tuning after finding out what the barrel is doing. Or just known run of the mill commercial brass? The data contained is current as of the date ordered and or shipped.
The updates occur as we obtain new information - sometimes in small increments and sometimes in large increments. IF you are looking for something specific email us and ask. We are happy to answer your inquiry. This software has been retired and is no longer supported. The software will be able to run on Windows XP, Vista, 7, 8 and You will need to provide the serial number of your original disk. The serial number provides required updated info for copright compliance.
Do note - it takes longer to upgrade discs are they are custom-generated in Germany by the programmer, so please allow 30 days for delivery.
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