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gschwertley
saddle soap
Posts: 420
(3/22/05 12:39 am)
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Proper Powder Selection
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There are a number of factors to consider when selecting a powder for reloading. Ready availability probably should not be the overriding factor in propellant selection, however. I'll get back to this further on.
With certain weapon designs, like semi-automatics, consideration must be given for the burning curve of the powder and how that effects the operation of the reloading mechanism of the weapon. This consideration usually limits a reloader to a more narrow range of powder choices than if loading for a bolt action, where the operation of the action is not a consideration. When this is the case, look for specific data for your specific weapon.
With bolt actions and other non-self-loading weapon designs, your orientation as to powder choice can be performance or economy driven.
Some people hold, generally speaking, that the powder that most closely fills the case and gives the highest velocity within safe pressure limits gives the best results in reloading. Richard Lee, in his book "Modern Reloading, states, "As a rule, a full case of the fastest powder that will yield maximum safe pressure gives the highest velocity.
Highest possible velocity is not always the only measure of a good propellant. In looking at the load tables in the various manuals, you can pick out the most efficient powder by looking for the one that gives a high velocity with the least amount of powder used. The charge may not fill the case, and you may not have gotten the absolute highest velocity, but you have gotten a high velocity using the least amount of powder.
Now, the "full case" theory in general applies to bottle-necked rifle cartridges, but not always to pistol calibers, particularly the older numbers originally loaded with black powder. However, with pistol calibers, you can use the "most efficient" method of finding the powder that gives a high velocity with the smallest amount used.
To get down to a couple of examples. Some time ago, my cousin Rich bought a 20 pound keg of Hodgdon 4198, a fine powder for many applications such as straight-walled rifle cartridges (like the .45-70) and wide application for reduced-charge loads. It is also a good powder for small-capacity cases like the .222 and .223. The problem was that when Rich got a .243 Winchester, having all of this H-4198, he dedided to use it in that caliber as well. There are loads for .243 using this powder, but it is very low on the list in terms of being an efficient powder. H-4198 is too fast for efficient use in .243; you reach maximum pressure long before you get up to anything like .243's potential for velocity. Conversely, when using a slow powder inappropriately where a faster powder would work better, you cannot get enough of the slower powder in the case to get up to a respectable velocity.
Another example is found with some 10mm Auto ammo that I was given recently. It was loaded with 180 grain plain-based SWC lead bullets, over 8.5 grains of Alliant Blue Dot. This propellant is wonderful for higher-power and magnum loads, and can even be used for lead bullets with a gas check. It was altogether inappropriate for use with plain-based lead bullets; leaving the Smith & Wesson Model 610 revolver barrel at way over 1,000 fps created quite a leading problem with only 18 shots fired. If you were to down-load this powder to a much lower velocity (even if you could find data that recommended this low of a charge), using Blue Dot would have absolutely no advantage over a faster-burning, more appropriate powder.
The two examples above both reflect reloading practices that favor availability rather than appropriate selection of powder.
A couple of other things to think about. It is generally felt that maximum loads do not yield the best accuracy; something less than the absolute upper limit often gives better accuracy.
Some people do not like lots of muzzle "flash". If this is the case, you may wish to stay away from ball or spherical propellants, which generally give more flash.
yockey5
Coffee Pot
Posts: 4861
(3/22/05 3:58 am)
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Re: Proper Powder Selection
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Thanks Gary, for this fine write up on powder and it's effects.
Don
Yesterdays Weapons forums
http:pub151.ezboard.com/bsteyrmannlicher
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mikmarjon
Attic man
Posts: 3518
(3/22/05 8:57 pm)
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Re: Proper Powder Selection
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I'm afraid that all to often My powder selection is generated by how much money I've been spending on guns. If I have a certain powder on hand that will work but isn't the best,sometimes I'll load it just because I can't afford to buy anything else That's why I usually have some 4895 and 4198 on hand,Those two will load most anything that I have for rifles. When I go to a show I'll try to pick up a couple of cans of each just so I'll have it for leaner times.
mike
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