What high pressure signs do you look for in an automatic rifle?

I have a new Ruger Target Rifle in 223 that I'd like to work up some loads in, but was curious about high pressure signs before I start.

Thanks,

It's a little tricky since you can't feel sticky extraction but otherwise it's the same as for a bolt gun. When the pressure gets really high, you can tear the rim off a case; it would be best never to get that high.

If you've shot factory ammo in it, you can use primer appearance and recoil as some bench marks. Also, as loads are increased, group size tends to shrink and then widen again; I stop where group sizes are the smallest.

About 25 years ago, when I was a rookie (I'm still not an expert ) I loaded 20 .280 Rem. ammos for a friend's 760 Rem. semiauto. Pressure was so high that the first round he (we) shot, the rifle jammed and I noticed in horror that the primer was gone from the blackened brass; of course we immediatly stopped shooting. That has been one of the main lessons I learned about reloading; I never experienced another blown primer since.