Factory ammo swelling

C

Cougar71

New member
Went to the range today with a buddy of mine, he has a brand new sendero chambered in 7mm mag. Was cold this morning, around 40, 42 degrees. Anyway, after each shot, he was having major ejection issues. Factory brass would swell and in a couple cases, the bolt let go of the case! Never seen this out of factory ammo before. Has anyone seen this before?
 
Have you got a picture of the case head to see if there are shiny ejector cutout marks/brass flow?

If no ejector marks I would next look at/suspect a rough chamber.
 
Was it difficult closing the bolt on the yet unfired rounds?
Have you measured the fired cases for unusual chamber dimensions?
Any suspicious markings on the cases?
Was there unusual recoil?
 
I'm assuming you're talking degrees Fahrenheit (you do mention cold). All else being equal it shouldn't be breech pressure - factory ammo is AFAIK rated at some sort of standard conditions (not necessary ICAO or Army Standard Atmosphere or whatever, but probably close to it), and your local conditions should cause pressures to drop.
 
Will the extracter make the bolt difficult to cycle? If it will im on the right track! what im saying is you cant chamber the cartridge you just fired! I can full length resize it and it chambers but you fire it and its almost like pulling teeth to eject it.
 
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High pressure or a chamber problem. Try a different brand of factory ammo first. Not an extractor if the fired brass from the factory ammo will not go back into the chamber.
 
How cold does it have to be to affect chamber pressure? Reason I ask is his rifle was in his truck all nite with temps from 25 to 42 Fahrenheit. He shot perhaps 12 shots and his barrel never got warm.
 
42 isn't cold enough to be a concern. Once you approach 0 or below you might start seeing lower pressures and speeds. If temps were near 100 you could start seeing some high pressure concerns.

Either a rifle chamber issue, or ammo issue.
 
This is beyond the scope of my abilities! I think I will find a gunsmith to take it to and let him figure it out. Fired cartridges should fall out of the chamber when you cycle the bolt!
 
I have seen this. In fact I was at the range today and we shot factory 7mm Remington Mag ammo in my son's gun that was "to hot" for my cousins 7mm RM. In my son's rifle it shot fine with no signs of high pressure. I would try a different brand of ammo before anything else.
 
What type of 7mm Mag?

7mm Remington Magnum?
7mm Weatherby Magnum?
7mm Remington Ultra Magnum?

Inquiring minds want to know.

Jimro
 
Certainly sounds like a pressure issue of some sorts. My first thought was maybe the throat is too short and you were touching the lands? Coming out of the factory a little too hot would be more likely.
 
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