How much virgin case growth is too much?

[goinghunting]

So I picked up some ADG 7 RM brass.

My Federal once fired brass is measuring 2.118 with the Hornady tool, started off around 2.106 +/- if memory serves. I thought that was a lot.

This new ADG brass is measuring 2.098 +/-.

At what point is the initial firing doing too much damage to this new brass...?

 

[Snuby642]

So you have 0.020 shoulder differance?
That is a lot to me but run 300blk,223,308 new brass at times. Normaly 0.008 ish.
In respect to size and power maybe the 20 thou is apropriat?

 

[goinghunting]

So you have 0.020 shoulder differance?
That is a lot to me but run 300blk,223,308 new brass at times. Normaly 0.008 ish.
In respect to size and power maybe the 20 thou is apropriat?

That's what I'm wondering. All the 6.5CM, 300wsm, 308 and 6.5-284 I've started with new brass has been within .008 or less prior to this 7 Rem Mag.

 

[goinghunting]

And yeah this new ADG has a .020 shoulder difference to the fired brass.

 

[Snuby642]

You could contact the mfg and ask if normal, i have no experience with a comparable round.
Have you looked up saami spec on it?

 

[Snuby642]

Saami says 2.1162-0070 on the 7 rem mag.
2.1092 min on the case. "Double check please".

0.0112 below saami min

To me a risk without further guidence, possibly a mfg problem.

 

[goinghunting]

So with the same tool I got 2.099 on New in Box Hornady Precision Hunter ammo... So size of the brass is fine I assume.

Is this chamber cut a little long???

 

[918v]

It is not uncommon to have .020” shoulder clearance on new belted mag brass. It does not hurt the case because it headspaces on the belt and you can bump .002” after that.

 

[Snuby642]

Thanks never had a belted magnum took a look at a case drawing and it was apperent even to me now thanks.

So when sizing those does it setback the belt?

 

[goinghunting]

Thanks @918v . I was thinking that was the case but figured I'd check here.

 

[918v]

Thanks never had a belted magnum took a look at a case drawing and it was apperent even to me now thanks.

So when sizing those does it setback the belt?

No just the shoulder. It then headspaces off the shoulder like a non-belted round.

 

[Snuby642]

Good to know in case I have to help someone.
I'm to old and wobley to shoot much of it would have to get the sled out.

 

[Cascade Hemi]

.022 growth for the first firing is fine. Just bump the shoulder back one or two thousandths and load. If the brass were growing .022 every firing you'd have a problem eventually. Most brass starts life undersized so it doesn't mean your rifle's headspace is out of spec.