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Normal Topic Weight variance between lots of powder. (Read 1436 times)
Old Soldier
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Weight variance between lots of powder.
Nov 22nd, 2019 at 11:26pm
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I have a good load in my 32-40 of 15 grains of 4227, so I'm throwing 15 grain charges thru my RCBS powder thrower. It throws + or- .10 grains. I'm happy with that. I ran out of recently manufactured powder. I had a CAN of older 4227. Put it in the hopper, threw 10 charges just to settle things, weighed the first charge and it was 16.5 grains. Thats a big difference! I was given the Can of 4227, so don't know it's history, but IF I remember right, it had not been opened. So, I dialed the thrower down until it was throwing 15 grains and went back to work. But it got me to thinking. My first thought was, wish I had a chronograph I'd load some at 16.5 and compare velocities with the new manufactured powder at 15 grains. I'm an old BP shooter, and that is all done by volume not weight. A lot of folks load with the old Lee scoopers, and appear to make it home at night. I've always considered not weighing smokeless a good way to lose a gun. Have any of you played with this? I know that a right answer is to work up a load with each different lot of powder. I am not doing that. Life is too short for that. Interested to hear your experiences. How do you handle it?
  

"White man have very strong Medicine. Shoot today maybeso kill you tomorrow." Esa-Tai Commanche warrior
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CW
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Re: Weight variance between lots of powder.
Reply #1 - Nov 23rd, 2019 at 1:29am
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IMR 4227
H-4227

There can be lot differences plus there are two products, IMR and H-

A good bit of opportunity to have the issue you describe.
Often when changing lots with max. or near max loads, start low and re-work the load.
I know, not what you want to hear. 
-CW
  
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jfeldman
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Re: Weight variance between lots of powder.
Reply #2 - Nov 23rd, 2019 at 11:01am
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I'd be mighty leery of that new stuff.  I've never seen that much variation lot to lot.  I've been shooting 4227 since about 1980.

Regards, Joe
  
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calledflyer
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Re: Weight variance between lots of powder.
Reply #3 - Nov 23rd, 2019 at 11:31am
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I agree with Joe F. I've shot that powder (both makes) since the mid seventies and only recall about a tenth of a grain from lot to lot, or from make to make. I rarely make an adjustment on the measure I use for one rifle, having long since found what my setup prefers. But, when I start each loading session with it I check for change on the scale. It's only a few moments to keep safe, so I do it, and then go happily forward knowing my stuff, and my safety have been confirmed- again.
Further, I have a piece of paper with the charge weight and powder denomination that is inside the hopper all the time. A hedge against the aging of the user, you understand.
  

happily ignored by J. "Sonny" Louis
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desert-dude
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Re: Weight variance between lots of powder.
Reply #4 - Nov 23rd, 2019 at 11:32am
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This is a good case for not only a chronograph but a pressure trace system. Wink
Actually the pressure trace and maybe the chrono are things a club should own to spread the costs. However, you can get into the chrono and the pressure trace system for much less than any of your good rifles.
Continuing along this line of thinking one, rather than strain gage every barrel, put the strain gage(s) on a std action and change barrels. A strain gage on either side of the mortice properly connected would double your sensitivity. Dummy half bridge and a strain gage half bridge. I know ... way too much information.
  
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calledflyer
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Re: Weight variance between lots of powder.
Reply #5 - Nov 23rd, 2019 at 12:39pm
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pie-in-the-sky stuff, DD. If you had a rich club the time to do it is still more than the simple expedient of tossing this one can of powder and replacing it with a known, fresh ingredient.
Here, even testing to the chrono is too chancy to make it worthwhile. Be safe, first and foremost. Be smart the rest of the time.
  

happily ignored by J. "Sonny" Louis
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ratseye
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Re: Weight variance between lots of powder.
Reply #6 - Nov 23rd, 2019 at 4:25pm
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A 10% difference is a bit more that usual I think but if it was a sealed can against an old open can you could be reading the solvents. I might be inclined to buy a new can and weigh it against volume just to see before I scrapped what you have. A chronograph might not see the difference within the normal range either. ratseye
  
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Schuetzenmiester
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Re: Weight variance between lots of powder.
Reply #7 - Nov 23rd, 2019 at 4:50pm
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Watching for primer cratering and sticky extraction are pressure signs that should show up long  before the rifle blows up.  Double charging a Ballard is a notable exception. 

I never charge a case without looking at the primer with the case pointed down.  A basic Ballard safety practice.
  

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calledflyer
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Re: Weight variance between lots of powder.
Reply #8 - Nov 23rd, 2019 at 7:09pm
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...or it could go like this.
  

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Re: Weight variance between lots of powder.
Reply #9 - Nov 23rd, 2019 at 9:38pm
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Both were IMR 4227. I backed off the charge to 15 grains weight. It struck me as a lot of difference.
  

"White man have very strong Medicine. Shoot today maybeso kill you tomorrow." Esa-Tai Commanche warrior
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