Damp cases velocity

[f2benny]

I reload 9mm with 147 gr plated over 3.4 gr of n320. Gets 890 fps usually from my guns. Last week a few round felt really weak. So i checked a few dozen rounds. This batch of ammo is all over the place. Some 700 fps even one that was 400. But most are over 860 fps. I may have bagged these cases still damp after wet tumbling them or had moisture from case lube in some.

 

Could that account for the variation? My press has a powder lock out so I don't think I could be way off in the powder and its usually pretty close to drop weight.

 

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[Foxbat]

I don't know what press you are using, but on Dillon the bushing, that holds the powder measure, likes to break at one particular location.  This is not immediately noticeable, but the throw weight starts fluctuating.  I had it happen more than once. 

[f2benny]

I don't know what press you are using, but on Dillon the bushing, that holds the powder measure, likes to break at one particular location.  This is not immediately noticeable, but the throw weight starts fluctuating.  I had it happen more than once. 

Yes this is a 650. I'll check that. Thanks.

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[Lazr111]

I loaded a batch of "not dry yet" cases a couple of weeks ago and had the same issues. .40 Major load using a 180 had a high velocity of 993 and low of 518...

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[perttime]

I once got a squib from "not dry yet" cases ...