Powder left in hopper for a week...accuracy problem??

[Crowe284]

I left som H4831SC in my charge throwing hopper for a week. The last groups I shot with this powder were .3 and .4. I loaded up 5 rounds today and shot them. Had a 2" group at 100 yds.

Now, to be clear, I throw a charge that is close to where I want to be and then trickle to get exactly 57 grains. The seating die has not come out of the press and I am using the same brass that I prepped all at one time.

Could leaving the powder in the hopper instead of in the sealed air tight jug cause this kind of variation?

Side note the brass was primed and sitting on bench open to atmosphere as well. I have done this many times with no ill effect. So thinking it's the powder. Also, I reload in a room in my house, so it's "climate controled" as far as temp is concerned. Obviously the rh varies in the house.

Anybody have any insight or similar experience. I don't know why I didn't just put back in jug....I always do.....

 

[Crowe284]

Also, scale was also checked before loading the rounds and was calibrated properly....and I'm sure it was the same powder. I know all about the safety stuff......I put a sticker on the hopper lid that also resides on the jug when stored. Just want to provide as much info as possible to get best openion possible. Thanks

 

[FURMAN]

I leave powder in the hopper all the time. I also leave primed brass on the bench until next reloading session all the time. I have never had any issues.

 

[Bullet bumper]

I can't see that kind of wild variation being caused by one week in a hopper .
It has to be something else . Try annealing the case necks as they may have just got too hard . Polish inside the case neck with an old worn bore brush wrapped in some fine wire wool and chucked in an electric screw driver low speed. Tap the case on the bench after to clean out any rubbish . Check the die system and make sure nothing has moved . Make sure the bullet seater is producing minimum run out on the bullet .
Try and determine if your gun shoots better with a slightly sized case body each reload or with more tighter fire formed cases . Some chambers shoot worse as the case gets tighter . It's rare but it does happen .

 

[redbullitt]

Doubtful. Just shot as consistently as ever on powder sitting in the chargemaster for a few weeks. Actually, shot notably well lol. Varget and 223 rem, not that it matters really. That primed brass should not be an issue either, as I do the same all the time.

Something is up. I agree on checking out the brass. Maybe you got unlucky and got a few oddball cases?

I suppose the powder could be an issue depending on humidity, say maybe its 90 pct outside and the window was left open for a long time. BUT it does not seem like the case here.

Was the scale calibrated last time you loaded? Probably yes, but good to be thorough.

How about you or the rifle/optic? Poor conditions at the range?

 

[Crowe284]

Thanks for the replies guys. I was also doubtful about the powder going bad. Will check the scope but I doubt it's that. Everything would have had to break loose on the last shot of a five hot group that went into .4 one week ago. My range is right out my back door. Conditions were fine and used sme front and rear off same bench. That was the last five pieces of prepped brass I had. Going to prep some more and shoot again. Going to shoot a group from that powder that wa left in hopper and a group from a new jug of powder (same lot) and see if there is any difference. Will also check everything on rifle and scope before shooting the groups.

 

[Barrelnut]

For what it's worth:
http://bulletin.accurateshooter.com/2008/09/tech-tip-humidity-can-change-powder-burn-rates/

 

[Lefty7mmstw]

how sure of your load are you? if the load is on the edge of being good, environmental changes between shooting sessions could very well have pushed the load into no bueno land...