Different powder lots


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Dithsoer
August 2, 2007, 10:58 PM
Has anyone ever noticed any differences in powders that are from different lots? I mean of course the same powder type but with different lot numbers. Ever notice a loss in accuracy, change in pressure or velocity, or are modern powders consistent from lot to lot?

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GP100man
August 2, 2007, 11:32 PM
i back off on my top end loads 10% & work back up on a new lot .
on lower & mid loads i only chrono if i precieve power being more than previous lot of powder.
my buddy that owns the chrono even measures velocity when loading a batch with everything the same ,claims it tells him when brass is work hardened& i can see when case mouths get stiff too ,on the target!!!


GP100man

Dithsoer
August 3, 2007, 04:13 AM
Well, my main concern is shifting accuracy. Say you have a really good load worked up, nice and accurate, and you find out that changing powder lots is the equivalent to changing powder types, that's what I'm afraid of happening. I'm just wondering if anyone has ever experienced anything this drastic, a significant change in accuracy.

Guy B. Meredith
August 3, 2007, 05:18 AM
Yes, I have noticed a difference from batch to batch. I typically run a new series for each new batch.

ftierson
August 3, 2007, 01:39 PM
Barrel harmonics plays an inportant role in accuracy, which has been one of the selling points of the BOSS system (you can adjust the barrel to the load and not have to work up the load for the barrel)...

It's all a function of when the bullet is exiting the barrel (at what point of the barrel whip does the bullet leave). Of course, this is mostly a function of velocity. Slower or faster means that the bullet is leaving the barrel at a different point in it's whip...

This being the case, any slight difference in burn rate, lot to lot, will affect accuracy. If you've already worked up a load for maximum accuracy and you then alter the velocity, the accuracy will 'suffer' slightly...

Of course, the temperature that you shoot the same ammo in will affect the bullet velocity and, hence, accuracy of the same load fired at different temperatures...

My point, of course, is simply that the quick answer to your original question about accuracy effects is, "Yes"...

But, since the temperature that you're firing the ammunition at will have a similar effect, the effect on accuracy due to lot to lot variation is somewhat unimportant.

However, since some powders display quite dramatic lot to lot variation, other aspects of the lot to lot variation are important to keep in mind. Like, for example, potentially blowing your gun up if you're loading to the very top edge of pressure to begin with...

Forrest

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