Resizing brass with live primers

I often pull bullets when developing a load for a new rifle or powder change or bullet change etc. Just use a neck resizing die and the rest of the case is the same as just after a full length resize.

I have an issue with having to use an expander mandrel after resizing which means the neck tension with your sizing die is way too high, and the inside diameter of the case neck is too small. I start my case prep after cleaning and annealing the neck and shoulder, then use separate full length case/shoulder resizing dies, then follow with a bushing neck resizer. This causes less mechanical working of the brass. Finish up with the neck trimmer (referencing off the shoulder) and everything is accurate and repeatable.
 
I have quite a few rounds from a rifle I have changed bullets on. I would like to pull all these bullets and reload them with the bullets I switched to. Do I need to deprime from them a safety standpoint in order to resize them or can I resize them? I do not use sizing stems but rather use an expander mandrel setup. Can the sizing process create pressure inside the case which will move the primers or some how ignite them? Thanks!
You can resize without worry. As long as you are not poking a recapping pin into a live primer there is no danger of discharge. Wear safety glasses though, just because it's good practice.
 
If your neck sizing only I use a Lee Collet die. I actually cut the decapping pin off the sizing mandril since I regularly use a separate decapping die anyway. Hope this helps?
 
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