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Posted: 3/29/2010 8:26:33 AM EDT
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So I'm trying to work up a load for my 5R. I have the powder charge down, and it's 1gr short of the max.
I want to go shoot some groups with different seating depths but I'm afraid of a KB. What are the cautions I should be aware of? Common sense would say a shorter OAL would compress the case thus increasing pressure initially. What happens when you get it closer to the lands? Shane |
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Quoted:
So I'm trying to work up a load for my 5R. I have the powder charge down, and it's 1gr short of the max. I want to go shoot some groups with different seating depths but I'm afraid of a KB. What are the cautions I should be aware of? Common sense would say a shorter OAL would compress the case thus increasing pressure initially. What happens when you get it closer to the lands? Shane Why are you wanting to mess with the length? Does the barrel have a lot of rounds through it? I usually don't mess with moving the bullet past suggested max OAL unless the barrel is showing signs of throat errosion. If your not getting the groups you think the gun is capable of I would get a different bullet weight or a different powder before I started messing with moving past max length. From what I understand both too short and too long can cause high preasure . You can seat in the lands if you want but generally your best accuracy will come off the lands a bit. I can't tell you where too long is but you can buy a tool that measures where the lands are. This might help. LINK |
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I have another tool, and have measured it. The lands touch (on this bullet) at 2.942 OAL, and the mag length is 2.810. .132 off the lands is pretty far, I would like to go about .020. This rifle's best group so far has been a .89", it should do better.
Just want my money's worth. 
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Your coal on the load, unless it's going below the minimal length, and your are compressing powder isn't going to be a hugh cause of over pressure. For example, my .308 FGM measure 2.720, my .308 155.5 Bergers are most accurate at 2.850 coal. I seat my rounds .0025 off the lands for that particular load. The tool I use to determine land start on my barrel is this. http://www.sinclairintl.com/product/10497/Bullet-Seating-Depth-Tools-OAL |
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Don't worry about seating deeper. The problem you have now is seating out closer to the lands, this will raise pressure, so you need to drop the charge. If you contact the lands drop the charge at least one grain.
The difference in case internal capacity from seating deeper in a bottle neck cartridge is miniscule. |
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