I guess this is a plug for Randy,you would do well getting some vent liners from him these do work great,if you don't shoot way over a hundred shots a year ,just put one in and forget about measuring.
I got some from him last year or maybe the year before that cannot remember.I kept 2 and gave the others to my friends.I just put the second one in last week (it didn't need changeing ) but I wanted everything right to test a hunting load.Have no idea how many shots I have gotten from the first one but it is been a lot .
I didn't shoot the savage as much last year (I shoot reg calibers a lot,at the range at least one day a week)but was way over a hundred,the year before I put over 1500 shots through 2 savages.That year I went through quit a few of the vent liners from savage.