223 AI Verticle

[Link]

I just had a 223 AI contender barrel built.

To fire form I loaded Lapaua cases with 27 gr H4895 using 52 gr Berger's. .010 jump. 14 T Tube.
The primers looked OK, CCI 400's
should I try CCI 450's?

My problem is I got perfect VERTICAL. 1/2 inch group's at 50 yds.

I was told this might be head space?
When you fire form will the brass take on the correct head space?
Should vertical go away after fire forming?
Could I jam a little to tighten up head space for fire forming?

thanks Link

I'm new at this but not as new as I once was.

 

[jamesinky]

Most of the time vertical means the powder needs increased. If you have pressure signs then you need to back off.

 

[queen_stick]

I've been told to jam the bullet hard into the lands when fireforming,set it so the bolt is hard to close). I haven't had to fireform anything yet, so I can't say anything based on experience.