How can one be sure they are operating within the acceptable presure ranges for a particular gun?
Sorry friend.....without a pressure barrel you can't!!!! Reloading requires you watch a long list of pressure signs.....and velocity is one of them and so is keeping within the reloading book specs.
I was told by a Barnes representative to use a micrometer to measure the case diameter just in front of the ejection ring on the case. When the case expands .0005" you are at max pressure for your rifle
You can do that.....but it's simply not true.....I also measure it but it don't do anything except to confirm other pressure signs.
In reloading circles it's called CHE...or case head expansion and was widely regarded as a good thing to do.....and it don't hurt to do it.....but in fact it's just one of many factors to take into account.....in and of itself it means nothing!!!!