Questions on shoulder bump for 7RM

[Highbrass]

Prepping some 7Mag brass and measuring with the Hornady shoulder gauge
my measurements are are all over the place.
Using a piece of new Hornady loaded ammo I measure 2.110
fired brass measures about 2.118
I get pretty heavy bolt resistance at 2.115
bolt seems normal at 2.113
I first bump the bulge out at the belt, then do a full length resize.
When I remeasure my shoulder I get between 2.114 and 2.009
Am I just being overly nitpicking or is there a real issue here ?
I am using a Lee die set and the sizing die bottoms out on the cartridge belt.
I have never really looked at my 7RM as closely and I have made very shootable ammo in the past.
So am I missing something here or is 7RM maybe just that sloppy ??

[charlie b]

How do they chamber and shoot? If the round chambers smoothly and shoots into small groups then don't mess with it.

I have had a case or two in a batch that would be difficult to chamber. I suspect those pieces of brass were slightly harder or thicker wall than the others so I sort them out.

Another thing to look at if you want to is annealing. Some cases may work harden more easily than others and 'resist' resizing more than the others. Annealing solves that issue.

[Highbrass]

I'm just starting to prep brass for a new barrel. The brass is mostly 1x fired.
After thinking on this a while I decided to start over from square 1
took the Decap /Resize die all the way up and brought the ram all the way up.
Then started down with the die a little at a time until the die just started to bump the shoulder.
then the ram will bottom out at the far end of stroke with the desired setback.
I probably have it set about as good as it's gonna get. It still varies .002~.003
I understand that the case headspaces on the rim but still has to have a bit of crush on the shoulder and that is how I'm approaching it.
I will be shooting later in the week so I will know soon enough.

[Dave Hoback]

I'm just starting to prep brass for a new barrel. The brass is mostly 1x fired.
After thinking on this a while I decided to start over from square 1
took the Decap /Resize die all the way up and brought the ram all the way up.
Then started down with the die a little at a time until the die just started to bump the shoulder.
then the ram will bottom out at the far end of stroke with the desired setback.
I probably have it set about as good as it's gonna get. It still varies .002~.003
I understand that the case headspaces on the rim but still has to have a bit of crush on the shoulder and that is how I'm approaching it.
I will be shooting later in the week so I will know soon enough.

7mm Rem Mag headspaces off the belt on the first firing, then people headspace off the shoulder, not the rim.:redface-new:

It’s like anything else. Keep tinkering and you will find accuracy with it.

[wbm]

Am I just being overly nitpicking

Yes.

[PhilC]

7mm Rem Mag headspaces off the belt on the first firing, then people headspace off the shoulder, not the rim.:redface-new:

Yep and how I've done it for years with my belted mag rifles, definitely improves case life.

[Robinhood]

Yep and how I've done it for years with my belted mag rifles, definitely improves case life.

Yes sir. If you don't do as Dave said then you run the chance of case head separation.

[Whynot]

If you are reloading brass that has been fired a different number of times or with different loads then it is not uncommon for different measurements-- even if you full size all the way down you will usually still get some level of inconsistencies because of spring back.

If it is once fired brass then you really shouldn't need to "bump the bulge" at the belt.... unless way over pressure or a chamber issue.

[Robinhood]

If you are reloading brass that has been fired a different number of times or with different loads then it is not uncommon for different measurements-- even if you full size all the way down you will usually still get some level of inconsistencies because of spring back.

If it is once fired brass then you really shouldn't need to "bump the bulge" at the belt.... unless way over pressure or a chamber issue.


Ahhh, The beauty of annealing.