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Discussion Starter · #1 ·
Measured 5 different bags of Winchester new 300 WM brass. The variance was astounding from bag to bag let alone within the same bag. Just another resounding reason to load once fired for accuracy. Variance was greater than 0.010 between 50 round bags and was on average almost 0.020 less than once fired brass. Just curious if anyone else seen similar discrepancies.
 

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Case Headspace Measurement - Another Anal F

If you really want a laugh, check out some belted mag brass sometime! You almost have to blow it open, and resize it before ever firing or many of them stretch enough to come apart in just a few loadings.
 

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Muddyboots said:
Measured 5 different bags of Winchester new 300 WM brass. The variance was astounding from bag to bag let alone within the same bag. Just another resounding reason to load once fired for accuracy. Variance was greater than 0.010 between 50 round bags and was on average almost 0.020 less than once fired brass. Just curious if anyone else seen similar discrepancies.
MuddyBoots,
Wouldn't you normally run the new brass through the full-length resizing die before using them? Would that not eliminate any shoulder variances originally observed?

Jim
 

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Discussion Starter · #4 ·
Headspace variance

Savage T,
Its not the case to case variance but the overall variance between lots. My once fired brass is on average 0.020 longer than new Winchester brass. I run then through full length but that only squares them up to each other. I was somewhat dismayed to see the headspace differences between lots was all over the map. I guess I wasn't prepared to see that much difference. Just got back from range and now I am even more perplexed. I shot the best group I have ever shot and it was out of new brass. It was in Remington Sendero .300 Win Mag with 165 Partitions RL-19. Average velocity was 3075 but damn near one hole groups at 100 yards. Go figure. I can't. So shooting this group today with new brass has basically set back my thoughts that new brass wasn't worth beans for accuracy since the headspace was no where it should be for my rifle. Sometimes I think you can over analize and events like today seem to confirm that anyway. I was even going to order new Tubb firing pin and spring and Timney trigger. I am now asking why would I change anything when it is shooting so good. I shot some 180 Partitions this morning as well and they were inside MOA with RL-25 at 3115 fps. Can't ask for much better. I have some of the new Accubonds in 200 gr but I was waiting until I had once fired brass for them. It is fun though to develop these theories on accuracy and humiliated by them at the range. I guess that is why I like to reload so much. It isn't always what you think it should be.
Muddy
 
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