20 October 2005, 07:12
FlyingAceWinchester cases...
I am a relative newbie to reloading, and since I was a little bored I decided to weigh a lot of Winchester brass in 25 WSSM. After culling a couple split necks I came up with 46 usable pieces. After some calculations I came up with an average weight of 209.9 gr. and extreme spread of 4.1 and a standard deviation of 1.08. Basically, my question is are these good numbers? If these are good numbers can I expect these kind of numbers from say Remington or Federal whenever they start manufacturing this cartridge? I know that a standard deviation of 1.08 would be excellent if we were sampling a population of velocities.
20 October 2005, 07:31
Steel SlingerThere's a very recent thread about weighing cases. You can probably find your answer there. Personally, I find that separating cases by weight doesn't have enough of an effect on my accuracy to bother with it. I don't shoot competition or BR either though.
20 October 2005, 07:32
rootbeerI flunked stats in school miserably (just signed the final and left-- I didn't have a chance, anyway), but I'd suspect you'd get a better grip on how good the brass is by also sampling "high-class" brass like Norma or Lapua. My gunsmith says anything other than premium brass is crap, much of it being out-of-spec by .003-.005 inches. In his world and in the rifles he builds, this is alot. For me, it's nothing to fear.
If you'd like, I can pick up any 25WSSM brass I might find at the range this weekened and send you some if you want it. PM me if you do with your address; reply here if you don't.
20 October 2005, 16:38
JaywalkerI suspect if you're weighing each, it's easier to segregate by weight than simply to measure and calculate sigma levels.
I think weighing cases is almost an indirect measure of the factors that affect accuracy when more direct measures are available. (I say "almost," because interior volume might be indicated by weight variations, and that could lead to pressure changes that affect accuracy, though I don't know how to determine when a critical level is reached.)
I find a more consistent measure of case quality is a measure of the variation of brass thickness around the circumference of the neck of a case, measured at three or four points. I like to keep the variation below 0.0015". Think about it; if one side's thicker than the other, how can the bullet be seated straight? That variation is very likely a manufacturing fault that extends though the entire side of the case, so "neck turning" isn't likely to correct it, either.
Jaywalker
20 October 2005, 17:08
Jaywalkerquote:
Originally posted by Jaywalker:
I suspect if you're weighing each, it's easier to segregate by weight than simply to measure and calculate sigma levels.
I think weighing cases is almost an indirect measure of the factors that affect accuracy when more direct measures are available. (I say "almost," because interior volume might be indicated by weight variations, and that could lead to pressure changes that affect accuracy, though I don't know how to determine when a critical level is reached.)
I find a more consistent measure of case quality is a measure of the variation of brass thickness around the circumference of the neck of a case, measured at three or four points. I like to keep the variation below 0.0015". Think about it; if one side's thicker than the other, how can the bullet be seated straight? That variation is very likely a manufacturing fault that extends though the entire side of the case, so "neck turning" isn't likely to correct it, either...
Jaywalker