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More range time Looking for Optimum Load

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8shots View Drop Down
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    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.
 
 
 
 


Edited by 8shots - June/29/2009 at 07:10
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kickboxer Quote  Post ReplyReply Direct Link To This Post 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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Post Options Post Options   Thanks (0) Thanks(0)   Quote Urimaginaryfrnd Quote  Post ReplyReply Direct Link To This Post 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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Post Options Post Options   Thanks (0) Thanks(0)   Quote sakomato Quote  Post ReplyReply Direct Link To This Post 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
 
 
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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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post 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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