jonn5335
Member
I fired factory federal 175 grainers through my 7mm and the cases grew from 2.490 to 2.505-2.510 after being fl sized is this much growth normal for once fired brass I did'nt think I would have to trim this brass so soon 
7mm rem mag case trimming
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JimKirk
Member
It is normal for brass to grow on each firing ...the first is usually the worst. Trim them back to 2.490.
Are you Full Length Sizng your brass.
I hope that you are using the brass shoulder for headspacing instead of the belt. If not you may have excessive stretching just in front of case web area.
I would back the sizing die out one full turn from ram contact... size a brass ... you should not be able to close the bolt on an empty brass. turn the die down in 1/8 turns until you can just close the bolt with slight resistance... turn the die 1/16 more and lock it down. Your brass will now last longer and stretch less. This is called partial Full Length Sizing.
Jimmy K
Are you Full Length Sizng your brass.
I hope that you are using the brass shoulder for headspacing instead of the belt. If not you may have excessive stretching just in front of case web area.
I would back the sizing die out one full turn from ram contact... size a brass ... you should not be able to close the bolt on an empty brass. turn the die down in 1/8 turns until you can just close the bolt with slight resistance... turn the die 1/16 more and lock it down. Your brass will now last longer and stretch less. This is called partial Full Length Sizing.
Jimmy K
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NeuseRvrRat
Member
PFL size like that^ or neck size
gamestalker
member
First cycle will always look like that. If your neck sizing, this will slow down considerably. I used to FL and quickly went to neck sizing to extend the life of my brass. 7mm mag or any belted magnum will headspace at the shoulder is you neck size. Other wise, your brass will get over worked by FL resizing during each session, pushing it back and forth at the shoulder. I was only getting 6 to 8 cycles before neck sizing, now I'm at 12 to 14 cycles from my brass. Another method is to use a collet die set up. A couple of guys in this site have said it delivers even more case life than necking, and eliminates having to bump the shoulder back every few sessions.
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