Depending on bullet, I set 55gr fmj plinkers for 2.250" as
@Jeff Porter mentions. My main reason for that was due to the cannelure being set inside the neck.
I want to post a pic to show what I describe to help assist my question. This is in a 308, so it is longer than the 223 being mentioned, but shows the problem.
Notice on the two Hornady 6.5 ELD-M bullets at max COAL, which is 2.825 per the data I use.
The 3rd bullet is a Hornady SST bullet which is a hunting round with a cannelure on it. The 3 bullet is seated just to get the cannelure inside the neck, but it is 2.670.
These cartridges have a .155" difference in COAL!
Next to them are 308 SMK and 308 TMK but neither have a cannelure.
What I was wondering is that it seems there's enough tension on the next to all me to seat the Hornady SST hunting bullet with the cannelure above the neck, but that is now how I've reloading in the past. On 223/5.56 I have always seated the bullets to get the cannelure inside the neck, and work my loads from there.
FWIW, in this pic below all the cartridges fit inside the mag, which is an AICS short action mag (DPMS/LR size which allows 2.825"). For bolt the mag is a convenience, IMO.
Certainly I can't rely on the same loads for each bullet in the same rifle, and this same problem can happen on 223, just that the 55gr fmj bullets I was using did fit to max spec. Mags make a huge difference on ARs, IMO, and pmags give the most problems. The metal DPMS style seem to work more reliably, in my experience.
Just to show, all cartridges fit inside and clear easily, but you can see how much lower the SST bullet is.
