The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Could use a good explination.Go | New | Find | Notify | Tools | Reply | |
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I’m in the intermediate stages of reloading. I’ve read a lot of information but coming up just a little short. I’m looking for a good explanation on the basic physics of the relationship between powder burn speed, bullet weight, and barrel length. Basically how does a slower or faster powder effect bullets of different weights and in barrels of different lengths, shooting at targets at different ranges? I know that I’m asking for a lot but I appreciate any help. | ||
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| One of Us |
Basically it is all tied to the maximum pressure at which we can operate. When you fire off the load all the little granules of powder start to convert to gas. As the bullet begins to move down the barrel it increases the volume for the powder gas to expand into and this in turn limits the pressure that the gas can achieve. A heavier bullet is simply slower to move which in turn means the increae in volume caused by the bullet moving is slower than is the case for a lighter barrel. This means the pressure will build to higher levels. To compensate for that we use a powder that converts to gas more slowly. In the case of calibres such as the 257 Wby, 264 Win etc, the bullet we use is light. However, because of the small bore diameter the increase in volume as the bullet moves down the barrel is small. For example, in a 458, when the bullet has moved 1 inch it has increased the volume about 3 times as much as is the case when a 264 bullet moves 1 inch down the barrel. Thus a 264 Win requires are powder than converts to gas at a much slower rate than for the 458. If we use powders that are too fast, such as varget/4064 etc in something like a 264 or 300 Mag then we have to reduce the amount of powder used so as to stay within alllowable pressure limits. This lower powder weight means the average pressure acting on the bullet is much less over the full length of the barrel and hence we can't achive top velocities. As to barrel length, in general the powder that givs the highest velocity in a 26 inch barrel is also likely to give the highest velocity in a 22 inch barrel. Where get higher velocity with a longer barrel for the same reason that a dragster is travelling slower at the 1/8th mile as opposed to the end of the 1/4 mile. Hope this help some. Mike | |||
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Should help! Very good, understandable explanation of a very complex subject! explanation "Bitte, trinks du nicht das Wasser. Dahin haben die Kuhen gesheissen." | |||
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 GOOD JOB!  rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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excellent.....a better explanation requires writing a book.....and most folks wouldn't read it! /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
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SS- Wow, That was an awesome explanation! I'm a newbie to all of this and you put me into a new groove on things regarding this complex relationship. I'm definitly going to save that post in my notes for a quick reference. Again, thank you for the information, I needed that too!!!!  | |||
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| one of us |
SS- Excellent explanation.  | |||
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The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Could use a good explination.
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