Shoulder Bump question from a new reloader

[Jason277]

Hello all, I read through a couple of related threads and I think I see my issue but looking to clarify, So I have only reloaded new brass as Im very new to hand loading. Im shooting a 6.5cm. I have 150 pieces of Once fired brass, some Peterson and Hornady . I have tumbled and deprimed my brass and now started to check my head space with a comparator . I noticed Im getting a range of numbers with in .002. Is this because the brass has only been fired once? Or becuase I was trying different powder charges? If so Im guessing I dont want to " shoulder bump" . Sorry Im a little confused on the resizing step. Thank you in advance Jason

 

[ColPenguin]

What are you comparing them to that they are within 2 thousandths, each other? You don't need to compare the pieces to each other. Compare measurements of the same piece before sizing and after sizing.

Do the resized cases chamber easy enough that you don't have to force the bolt? It either fits easily in your chamber, or it doesn't. The cases are probably not fully formed to the max dimension after the first firing. As long as you're not dramatically overworking the brass then you might be overthinking this.

If the case doesn't quite fit, or the brass is getting longer, then screw the die down a hair more and size another piece again until cases fit your chamber.

 

[Axlrod]

Without knowing how your brass fits in your particular chamber, you can't determine how much to bump your shoulder, if at all. A lot of people will say to bump .002. Saying that is like cutting a board, without measuring the spot you want to put the board.
If you are comfortable with stripping your bolt- removing the firing pin and ejector. There is a simple way to adjust your dies.

If not, the best method for a hunting gun, is to set your size die for camover, following your die directions. And full length resize all cases.

 

[MTSLW]

It's not unusual to have brass measure a thou or two different, especially after the first firing.

What matters when shoulder bumping is that you can close your bolt without feeling an increase in resistance. Should be no difference between a loaded round and sized brass.

Try the short and long fired cases in your rifle and see if the bolt feels tight when you close it, then bump the shoulder back accordingly. Generally you want to size the shoulder back on fired brass that feels tight .002-.003". You shouldn't have any issues unless you are bumping more than .005" back.

If you want to see if the die is contacting the shoulder, use a lighter to smoke it and then slowly screw the die in. You will probably see the shoulder actually get longer as you size it down and before it contacts the shoulder.

Good luck with the journey!