7stw
Well-Known Member
I would like to talk about bumping the shoulder back .003 or .0035. Want to make sure I understand what is going on here. What I think I know is you take a fired case out of your STW and measure it with a Hornday Head Space gauge and caliber and you write down the measurement. You then set up your die so when you resize the case your measurement is .003 less than your first? I hope that's it.
Also can this be down with a neck sizer die or do we have to use Full Length sizer die. I have both but have never understood what bumping the shoulder back means or why we do it. Thanks Rick
Ok Rick, I'll attempt to translate my thinking into text, but you are on the right track. You do not have to do this to the neck die. The neck die ONLY sizes or resized the neck only, and doesnt contact the body. But you are spot on with your approach, and understanding. I have another method that works very well, that is timeless, and guys have been doing it for years, ( me too).
Smoked shoulder anyone? Take a once fired case, lube the sides ONLY, not the shoulder or neck! Take a candle, or a cigarette lighter, and hold it under the shoulder and neck area on the case, and don't touch it. You are trying to soot it up completely. It does get warm, so use pliers if needed. Now, while it's cooling a little, back off your resizer lock ring, and unscrew it about two turns. Now comes the tricky part, but not really. Run the case up into the die and back out. Note the soot on the top of the shoulder. Keep gradually screwing DOWN on the die til you see a change in the soot on the top off the shoulder. When you just see a change in the soot, you are at about zero. I usually give it about another 1/4 turn down. Lock up you lock ring, and re adjust your expander to center, and just to the point where it pushes out the primer.
Sometimes, you may need to do this a few times, so have a few pieces of brass on hand. The better the " soot print" you have, the better you will be able to read it. If you feel comfortable with the Gage, that's fine. If you want to check yourself, this is the way to do it. This normally yields about .003 shoulder bump, +-.
IF, you feel that the chambering is too stiff, you may have to turn it down a little more. Once you get it set correctly, it will extend your brass life, and make the rifle more accurate.
This is a trial and error exercise, but once you find that sweet spot, you are golden!
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