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Posted: 7/29/2013 7:59:58 AM EDT
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Maybe this has been asked before, but this is sort of theoretical question. In a perfect world, assume you are shooting the same rifle under the same conditions using the same bullet, primer, brass, COAL, etc. The only difference is the powder. If you achieve the same velocity with the different powders, shouldn't the accuracy be the same? The bullet should be exiting the barrel at the same point in the barrels harmonic frequency. What else could effect the accuracy?
I'm just curious what everyone has to say. Obviously you need to think about overpressure and safety, but if powder x is cheaper than powder y, it would be good to know. |
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Quoted:
If you achieve the same velocity with the different powders, shouldn't the accuracy be the same? The bullet should be exiting the barrel at the same point in the barrels harmonic frequency. What else could effect the accuracy? The pressure curves could be totally different and still yield the same velocity.... so that same velocity does not translate into the same harmonics at all. |
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No, maybe, barrel harmonics are more complex than just velocity.
http://www.varmintal.com/amode.htm |
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Quoted:
The pressure curves could be totally different and still yield the same velocity.... so that same velocity does not translate into the same harmonics at all. Quoted:
Quoted:
If you achieve the same velocity with the different powders, shouldn't the accuracy be the same? The bullet should be exiting the barrel at the same point in the barrels harmonic frequency. What else could effect the accuracy? The pressure curves could be totally different and still yield the same velocity.... so that same velocity does not translate into the same harmonics at all. +1 there are to many unknown variables that come into play. |
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Quoted:
im a novice in the reloading buisness, but ive always heard that powder doesnt really make that much of a diffrence as long as it achieves the same pressures. although Im sure theres a lot of experianced loaders out there that would argue that point. Yes like all of them. 
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Quoted:
im a novice in the reloading buisness, but ive always heard that powder doesnt really make that much of a diffrence as long as it achieves the same pressures. although Im sure theres a lot of experianced loaders out there that would argue that point. Interesting. Mind sharing where you heard this? Also, how would you and I know if our loads generated the "same Pressures"? I do not have access to pressure testing equipment, do you? |
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Read through some manuals. You will find that you can achieve the same velocity with different powders using slightly different charges with them. You can load up or down with a faster or slower powder and achieve the same velocity- but with very different pressure curves. |
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Quoted:
Interesting. Mind sharing where you heard this? Also, how would you and I know if our loads generated the "same Pressures"? I do not have access to pressure testing equipment, do you? Quoted:
Quoted:
im a novice in the reloading buisness, but ive always heard that powder doesnt really make that much of a diffrence as long as it achieves the same pressures. although Im sure theres a lot of experianced loaders out there that would argue that point. Interesting. Mind sharing where you heard this? Also, how would you and I know if our loads generated the "same Pressures"? I do not have access to pressure testing equipment, do you? And all pressures are not the same. When does each powder reach peak pressure? |
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As stated my many others, the timing of the pressure peak seems would make a big difference.
I'm no expert at this but here are some others I could think of: powder type effects consistency of ignition volume fill in the case effects consistency of ignition burn rate of powders respond differently to temperature |
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Quoted:
The pressure curves could be totally different and still yield the same velocity.... so that same velocity does not translate into the same harmonics at all. Quoted:
Quoted:
If you achieve the same velocity with the different powders, shouldn't the accuracy be the same? The bullet should be exiting the barrel at the same point in the barrels harmonic frequency. What else could effect the accuracy? The pressure curves could be totally different and still yield the same velocity.... so that same velocity does not translate into the same harmonics at all. I would lean this way. If it takes higher pressure to achieve X velocity it can change how your barrel reacts. |
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Quoted: Maybe this has been asked before, but this is sort of theoretical question. In a perfect world, assume you are shooting the same rifle under the same conditions using the same bullet, primer, brass, COAL, etc. The only difference is the powder. If you achieve the same velocity with the different powders, shouldn't the accuracy be the same? Answer to this is NO. Reason is barrel friction is different as is the acceleration of the bullet... Every barrel I have ever worked extensively with had a favorite powder. The bullet should be exiting the barrel at the same point in the barrels harmonic frequency. Unfortunately also a NO. Different powders have different speeds of ignition, and therefore harmonize differently. What else could effect the accuracy? I'm just curious what everyone has to say. Obviously you need to think about overpressure and safety, but if powder x is cheaper than powder y, it would be good to know. |
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Given: You can develop loads with different powders that develop the same velocity.
You would still have differing pressure curves- One powder might result in 10K PSI at the muzzle, while another might result in 14K. Ever see 2 cars drag racing where car #1 accellerates hard off the line and then car #2 catches him further down the track, both finishing side by side (same speed)? Bullets can do the same thing based on the pressure curve. If you were to draw a pressure curve the length of the barrel, the velocity would be a function of the area under that curve not just the pressure at the muzzle. One curve could peak earlier (Like car #1) with higher max pressure, and the other (car #2) could have a lower, flatter peak. |
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