I perplexed about something and would like to see if someone can explain this to me. So I recently subscribed to the bumping the shoulders back concept over the neck sizing concept. Since I'll be doing this I decided that I would dedicate one full length sizing die to this particular rifle and then just lock the die down.
So I have a bunch of fire formed brass. I take it and I size. Not what I need to get to so I dialed the die down and sent the case back in. No change. So I grab another piece of brass and send it into the die and it is different from the first.
So basically what I've found is that I can't change the sizing once I've sized the brass. It took me seven pieces of brass to get it right. Once I got it right I was able to produce as many identically sized pieces as I wanted.
Is this what is supposed to happen? Why?
I'd expect to be able to move the brass as many times as I want. As an example I had one piece of brass that was .007 under SAAMI I sent it up into the die after I got it all set and produced many .002 under SAAMI pieces but I wasn't able to move this one. Is this what is supposed to happen?
If I haven't explained clearly please let me know and I'll try again.
thats known as springback!, it happens because that piece of brass is harder and more brittle than others, you size it down the same as the others but it springs back more closer to its original size, thats why its advantageous to you to keep all your brass the same, load'em up the same amount of times, shoot them all before reloading them again, keep them all the same make, lot # and such.
ok, the piece that was .007" under size, will not get bigger by resizing ( hope this is what your wanting) now if it will go off it'll be back to chamber size afterwards, if it will not go off, you'll hafta pull the bullet and resize it up one calber then size it back down. this makes a false shoulder to hold the headspace while its formed in the chamber.
Let me try RR
statjunk, go out and kick a fender on your beamer.
Notice this did not leave an actual footprint..
It dented a little, but the fender sprungback some, right?
You think kicking it again would reduce the dent?
Now while your car is out for repairs, re-read your basic reloading book, or search the forum for anything in the world to be learned.
This tool will allow you to set up your sizer die the same every time. Though most shooters feel they need headspace off the shoulder the fact is if your rifle has the proper HS from the case head to the bolt face, +.002 / +.003, there is no need to even touch the shoulder, +.001 is generally all that is needed.
I cringe at the thought of even touching the shoulder and disturbing my perfectly fire form cases that match my chambers dimension exactly. Not only does this practice of bumping the shoulder back play hell with run-out with the case neck, it also adds way more HS than is necessary which over works the brass. Larry's sales pitch is this gage will help you accurately set the shoulder back and it will, I on the other hand use it to make sure my die is not touching the shoulder. I find if I only re-size the neck and the body of the case, after two firings, my die barely touches the body and the case shoulder will stay true to my chambers OAL measurement. Every case will measure the same at the shoulder as long as I am using the same powder charge. If I'm trying to work-up loads the pressures are always changing and that will be apparent, as the shoulder measurements will not be stable. However, once I settle on a charge that is showing promise all my cases will measure the same and dialing in the load is real simple.
If you already have a way to accurately measure your case shoulder you could give this a try. I own Larry's HS gage because it makes measuring fast, easy and can be used to take other measurements as well.
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US Army 79 - 85, 368th Combat Battalion, Sarget Spec-5, Combat Engineer
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