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More range time Looking for Optimum Load

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Category: Firearms, Bows, and Ammunition
Forum Name: The Range Report
Forum Description: Shooting results/targets, range conditions (Online data book)
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Topic: More range time Looking for Optimum Load
Posted By: 8shots
Subject: More range time Looking for Optimum Load
Date Posted: June/29/2009 at 06:52
After Sakomato's post on Optimum or tolerant load, I decided to re-look at the load I had developed for my 308Win.
I firstly kept the 44gr S335 and played with seating depth. I went for a longer seating depth then my 69,9mm. The 69,9 mm remained the better seating depth. I shot one screamer, around 1/4 inch. See top right on second target. That is 5 rounds in there!
The next day I reduced the powder and seating depth to 68,9mm. The shorter cartridge, now about 100 thou (2.7mm) off the lands. 2.71 inches agains a maximum chamber of 2.81 inches.
This deeper seating and a reduced charge gave a much more stable load. See target 3. The 43.3 gr of S335 with a OCL of 68.9 again produced a screamer.
All the impact points of the different loads are very similiar, so this indicates a stable zone for the rifle.
I have settled on the 43.3 and 68.9 load.
 
 
 
 



Replies:
Posted By: Kickboxer
Date Posted: July/16/2009 at 18:19
8shots, that looks like you hit the mark.  Every time I look at someone's experiements like this, it makes me want to reload again.  Factory stuff is very good nowadays, but also very limited.  Sometimes the rifle and the factory stuff click, sometimes they don't.  It is good to see your results.  Thank you.  

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Opinion,untempered by fact,is ignorance.

There are some who do not fear death... for they are more afraid of not really living


Posted By: Urimaginaryfrnd
Date Posted: July/16/2009 at 20:46
Very nice  - I suspect that level of accuracy is adequate for the elephants but you better tighten it up a little for the rhinos.  Reloader

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"Always do the right thing, just because it is the right thing to do".
Bobby Paul Doherty
Texas Ranger


Posted By: sakomato
Date Posted: July/16/2009 at 22:51
Hey 8
 
Glad to see you are shooting so well.
 
Got a question though.  The lower right on the 3rd target looks like a scatter group but it is different from the rest with a 69,9 seating depth.  Now varying the seating depth will slightly effect velocity, a deeper seating depth will lower it and a longer OAL will increase velocity.  So even though it looks like a scatter group it may have the same velocity as one with a deeper seating depth but with a higher powder charge.
 
Did you run them over a chronograph?  The 43.4 load with the shortest OAL may have the least velocity of any shown.
 
Supposedly the OCW load is 1.5% above the scatter group
 
http://practicalrifler.6.forumer.com/viewtopic.php?t=954 - http://practicalrifler.6.forumer.com/viewtopic.php?t=954
 
so if the 43.1 was the scatter group or close to it then the 43.7 load may be the best.
 
 


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Guns only have 2 enemies, rust and politicians


Posted By: 8shots
Date Posted: July/22/2009 at 10:19
Sakomato, soory, I did not chrono the rounds. I kept all the rounds at 69.9 during loading and brought the seating die with to the range. I saw an immediate improvement when I shortened the OCL at the range, this is why I went for the shorter OCL. I will try the 43.7 again and see how it stands up.



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