How much difference does once fired brass make?

Joel said:
Is that because as has been stated here, it takes energy to expand/reshape a case?
Click to expand...

Correct... and that will vary depending on the difference between the size of the new case and the chamber. SAAMI allows for some significant differences and manfs can push this in both directions.

When I was shooting alot of 308win in my F class rifles, there was no way I was just going to blast a couple of hundred bullets down a barrel to form brass. So you 'worked' up a load for the new brass to give you some practise ammo. Often, it could shoot well enough for competitors to use in local matches too.

Another approach was to form the brass using a mild load and cornmeal/cream of wheat. A good practise if trying to 'improve' or really change the shape of the case.... reducing the chance of risking damaging the case web if formed too aggressively. Still, the final pressure firing was needed to set the case.

With newer chamberings, I believe tolerances are going to be held tighter and why so many factory rifles and factory ammo are shooting really well in these new offerings vs some really poor performance with historical chambers/ammo combos. One of the best examples, the 6.5 Creedmoor.... vs the ole belted magnums

YMMV

Jerry
 
Mystic Precision said:
Correct... and that will vary depending on the difference between the size of the new case and the chamber. SAAMI allows for some significant differences and manfs can push this in both directions.

When I was shooting alot of 308win in my F class rifles, there was no way I was just going to blast a couple of hundred bullets down a barrel to form brass. So you 'worked' up a load for the new brass to give you some practise ammo. Often, it could shoot well enough for competitors to use in local matches too.

Another approach was to form the brass using a mild load and cornmeal/cream of wheat. A good practise if trying to 'improve' or really change the shape of the case.... reducing the chance of risking damaging the case web if formed too aggressively. Still, the final pressure firing was needed to set the case.

With newer chamberings, I believe tolerances are going to be held tighter and why so many factory rifles and factory ammo are shooting really well in these new offerings vs some really poor performance with historical chambers/ammo combos. One of the best examples, the 6.5 Creedmoor.... vs the ole belted magnums

YMMV

Jerry
Click to expand...

The part I bolded is something to keep in mind whenever you're looking at SAAMI or anyone else's data. There are ALWAYS a plus/minus range, and stacked tolerances can (and will) bite you in the butt. - dan
 
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