AR Comp compressed loads?

[Shooter31]

1st time loading AR Comp.
Using Starline brass and 123gr SST's
Book says 27.7 and 28 grains are max but nothing about being compressed.
I'm hearing it to start compressing at 26.5 grains. Is this right, just want to check with some of yall.

[grendelnubi]

I'm using hornady brass and with the 123 gr SST seated at 1.678 Ogive to base, 100% compacity, non compressed, it is ~25.7 grains of AR Comp. With the brass full to rim it measures 31.8 grains of AR Comp. This was not measured scientifically so take it for what it is. I just thought one day it would be good to see what 100% capacity was using AR Comp with specific projectiles loaded at seated depths and this is what I got.

Hornady and Starline has a little difference in wall thickness. One has a little more volume than the other.

[Shooter31]

Thanks, maybe thier not compressed but they definitely have thier seatbelts on. Lol

[Bobke]

I?m running 27.2 ARC in three different barrels with excellent accuracy and low ES/SD with 123 Sierra, tipped and pointed BTHP?s. OCD, probably. That said, between 2.25-2.27, there is definitely compression with this specific bullet and charge, and several short stokes on seating handle are required to stabilize BTO/OAL. Nosler CC?s, 120-123 Scenars and others can be loaded either heavier, or with less compression at the loading point.
I?ve spent the last week playing with neck diameter and it?s effect on bullet movement in seating and once bolt is released. More OCD for sure, and not sure there is one simple answer, but have found .003-.004 works to limit creep, without affecting accuracy negatively. Still working with it.