7mm Mag brass stretch?

TimberHunter

WKR
Shoot2HuntU
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Nov 7, 2018
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Recently picked up a new savage 110 LRH in 7mm mag. This is my first belted mag that I will be reloading for. Is this normal case stretch when shooting factory ammo?

Hornady whitetail and superformace ammo shoulder: 2.107”
The above ammo after being shot through my rifle: 2.122”

Brass stretch= .015”

Shoulder measurements were taken using a Hornady headed comparator gauge


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Pretty typical for a belted case especially a factory chamber. The first firing the case headspaces off the belt and grows quite a bit. After the first firing you can setup your die to bump the shoulder .001-.002. Be sure the check the brass to see that it chambers. You may need to size all the way to the belt after a few firings also.
 
Thanks all. When shooting brand new brass that I loaded, will I see much of an accuracy difference vs once shot brass in my chamber that I FL sized with the shoulder bumped back a few thousands?


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Thanks all. When shooting brand new brass that I loaded, will I see much of an accuracy difference vs once shot brass in my chamber that I FL sized with the shoulder bumped back a few thousands?


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Usually accuracy improvement is minimal or even negligible, but your ES and SD numbers will noticeably tighten up. I agree with all other answers too, that growth is pretty typical and depending on how tight your chamber is you may need the Larry Willis collet die to size the body above the belt to get more life out of your cases. Look up belted magnum "case bulge", it's a PITA.. :rolleyes:
 
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