Hey BS!
It really helps save some barrel life with chamberings like the above; 7mm RUM. I'm not into shooting a couple hundred rounds down the bore with so so accuracy just to fire-form and lose about 20% of the barrel life.
It also really helps when you are forming a new batch of cases for a competition rifle. I usually do 500 new cases.
If you do load development in NEW cases that are not formed to your chamber, all bets are off.
Have a nice day boxer!
