Advice about pressure signs

[biodsl]

First, how fast can you push a 123gr bullet out of your 20" barrel before harming your brass? I'm trying to see if I have unrealistic expectations for my barrel and this input would go a long way to helping me understand that.

I had a 20" Lilja (which is actually 19.5" of barrel and chamber). My 123 Amax load of 31.2gr of CFE223 was around 2450fps standard pressure and temp. Only the slightest hint of ejector marks on some brass.