nosler 7mm rem mag shoulder grows .022 after first firing, normal?

[J E Custom]

I also just started working up a load for a 7mag. I made a fire form load with 162 amax jammed into the lands and a light charge (starting load in the book). used my magneto speed and got 2600fps. This blew the shoulder forward .016-.019. I then used a redding body die set just short of touching shoulders. This lengthened the shoulders to .022-023. At that point I tried to chamber the brass and felt a fair amount of resistance on closing the bolt. A lot of my brass ended up at .020 after 2nd firing and with a little springback I think this is about .001 short of my actual chambers shoulder. I have had good luck using a redding body die and a lee neck collet die for several guns.

When you jam a bullet into the lands, it increases the pressure over the same load with some jump. The beauty of the belt is that you don't have to seat the bullet into the lands to fire form or to shoot new brass the first time.

Belted cases will always lengthen the first time they are fired because of the case size compared to the SAMMI chamber size for proper function based on the intended design, but future case growth is solely dependent on the sizing after that.

There are so many different philosophy's on sizing belted cases that address one problem but not another that make it hard to reach a consensus on the best way to load belted cases that all I can say Is
Belted cases are not hard to load and can be very accurate if loaded correctly. Case life can also be as good as many shouldered cases, So a person has to decide what he wants from a belted case.

Any sizing that reduces the case dimensions smaller than your chamber dimension, will shorten case life.

Just my opinion

J E CUSTOM