Went to the range this morning and shot the 7 rounds of 7x57 that I made up with the false shoulder. They stretched but not near as much as I would’ve liked. Using the Forster Datum Dial, the brass before firing measured X.X31”-X.X37”. After firing, the brass now measures X.X38”-X.X44”. I’m guessing an average of .007” stretch, but I need more.
I found some Speer 145gr HPBT Match bullets hiding in the garage. I’m going to use these and load up a little hotter load, and see what happens next. Out of all the brass I have, the Hornady was definitely the shortest, the RP, FC, PPU, and S&B don’t have near as far to stretch to fill the chamber.
I think I will try 5 pieces of the S&B brass next. I’m going the write down a before and after measurement for each piece to get a better idea of what is happening. After some thinking, I’m going to move the false shoulder out a little more too, make it more of a “crush fit”, and see if that helps too.
On a side note, this load with shoulders all over the place, and a false shoulder formed, shot respectably.
JTD
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