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.270 velocity variations

 
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  #22  
Old 12-14-2009, 08:17 AM
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Join Date: Nov 2007
Posts: 78
Re: .270 velocity variations

How close is you crony to the shooting table? Ive had some funny readings in certain light conditions when shooting with the chrony to close. i chalked it up to the exhausting gas and not quite right angles on the chrony.

There was a series of articles from Ken? ohler in 2007-2008 shooting times magazine that talked about the way chronographs work and how errors are introduced... seems that the distance between the eyes is very critical. loose construction and many other things put a surprising error in the works. (like shooting across a folding type chronograph that isnt all the way open. think sitting on a table with some junk under one end)
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  #23  
Old 12-22-2009, 06:18 PM
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Join Date: Mar 2008
Posts: 139
Re: .270 velocity variations

OK guys.
I had my powder charges weighed by a commercial grade pharmaceutical research scale.
My RCBS Charge Master is weighing dead on.
One weight was 45.5 gr on the ChargeMaster...pharmaceutical scale 45.53 gr.
the other was 52.3 gr on the ChargeMaster ... pharmaceutical scale52.22 gr.

So..we are talking about less than part of a single stick of IMR 4350. There is no way a balance scale can match this.

Now that I know the scale is right on I have to figure out what else can be giving me the velocity variations. Maybe it is the chronograph.
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  #24  
Old 12-22-2009, 10:35 PM
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Join Date: Jun 2007
Location: Central Washington
Posts: 491
Re: .270 velocity variations

Quote:
Originally Posted by kstrick View Post
OK guys.
I had my powder charges weighed by a commercial grade pharmaceutical research scale.
My RCBS Charge Master is weighing dead on.
One weight was 45.5 gr on the ChargeMaster...pharmaceutical scale 45.53 gr.
the other was 52.3 gr on the ChargeMaster ... pharmaceutical scale52.22 gr.

So..we are talking about less than part of a single stick of IMR 4350. There is no way a balance scale can match this.

Now that I know the scale is right on I have to figure out what else can be giving me the velocity variations. Maybe it is the chronograph.
Thanks for reporting back! I have the utmost confidence in my Chargemaster and know it weighs powder more accurately than I do with a balance!

Keep working on those variations!

Bill
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  #25  
Old 12-22-2009, 11:04 PM
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Join Date: Mar 2008
Posts: 139
Re: .270 velocity variations

The chrony is about 8 - 10 feet out. I am going to move it to 15 feet and see what happens.
I will keep working on this. Guess it just means more reloading and more trips to the range....sigh. Well better get out to the bench...yeee HAAA!!!
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  #26  
Old 12-24-2009, 05:35 PM
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Join Date: Dec 2009
Posts: 104
Re: .270 velocity variations

Are you seated too deep? I'd play with the seating depth first. Sort your brass by weight as well. remove as much of the variables as you can. I prefer h4831 in the 270 and from summer to Nov I see 25fps ES. I would guess that if those 2 variables I suggested don't improve go to the 215 match primer and check The 270 in my testing does best with a mag primer. It's a long for bore powder columm so put more fire to it.
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  #27  
Old 12-25-2009, 02:59 PM
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Join Date: Mar 2008
Posts: 139
Re: .270 velocity variations

Thanks
I seat right off the lands. I mostly shoot Bergers. I have not tried 4831. What kind of velocity do you you get? I mostly load 140s but I also have some 150s.
I have sorted brass an keep it separated into lots. I do not mix brass from different manufactures.
Merry Christmas
Ken
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