I don't know much about the raw technical details but the answer is yes some of us do chamber the barrels for a specific round. For example, when I found myself with five rifles to build and spent a year around hear soaking up everything I could I started buying tools. My first rifle was a SAI M21 and Inwas well stoked up on BH 175 gr match ammo. I don't know what SAI used to chamber the M21 I would assume it was a .308 match reamer. So considering I had all this 175 ammo and planned on using nothing but because all the rifles I built have Krieger match barrels and all the match mods, i started my finish reamer education. I was surprised to find out that there was a lot to know, more than I cared to learn actually. After speaking to helmut the production manager at Krieger, he suggested I use an obermeyer .308 match reamer considering the 175 grainy SMK rounds I would be using. After he confused me, I called a couple of reamer manufacturers at this point I was in reamer info overload. I was fortunate enough to get hold of Ted Brown and Art Luppino (cactus comet)that afternoon and they both straightened me out a little bit. So I decided to purchase an obermeyer .308 match reamer from pacific tool and guage for a couple of reason. One Krieger uses obermeyer reamers to short chamber there barrels two after talking to boots obermeyer he explained that he designed that reamer specifically for the M118 projectile which is a 173 grain pill and close to the 175 gr smk's. Dave at ptg tried talking me into a match .308 reamer. I would imagine because he had them on the shelf ready to go out the door as opposed to having to make thnx obermeyer. The two features that are different that stick out in my mind is the obermeyer has a 2 degree cone angle and a little longer throat for the longer round. Now back when inwas taking notes I could tell you what the cone angle was but I simply forgot. It's lime studying for a history test you learn it then dona brain dump. I never like wasting my time on middle eastern or European history when I could have been taking another math class but that's an entirely new chapter. Bottom line is I would like to think I Taylor my chambers to my round. Some way have a differing opinion and a great deal more knowledge about finish reamers than I do but they are not cutting my chambers or shooting my rifles. There are only a few finish reamers to choose from for this rifle. .308 .308 match obermeyer match. On a side note the obermeyer ptg made for menwas the first one he made in several years. I don't know if there are to many left out there but they can be had.
Gee wiz I wonder who chambered noexperts barrel? Ha ha . You better like it! That barrel was twisted on with love bruda.