Help a newb, please!!

[JustMissedIt]

I fired 60 rds of factory 108 ELD’s in my brand new 6mm Defiance/Bartlein action. After fire forming I measured my shoulders at 1.532 in my .400 headspace gauge that came with my Whidden Dies. I bumped all 60 back .002 to 1.530. Then I started my loads with 39gr of H4350. Today, I shot those 60 rds. My groups were .4” to .6” (12 sets of 5 shots. I measured those cases again and they were still at 1.530. Should they have moved back to 1.532?? Forgive me and call me an idiot if I’m off track. Help.

 

[straightshooter1]

If you're not annealing your brass, it could be that the brass is at a point where there's that much spring back now . . . ??? If your 1.530 cases chamber ok, like without the bolt closing stiffly, then you should be ok to use them at that 1.530. As you continue to fire them, always keep an eye on that.

 

[918v]

It’s not unusual for the shoulder length to remain where you set it when using light starting loads.

 

[918v]

With light starting loads, the last thing you see in the above pic does not happen, meaning the case stays forward in the chamber. The case does expand and seals the chamber, but it does not stretch back to the breech face. So the shoulder length does not change.