I see now, I havn't had the vent holes getting bigger but will keep my eyes on it.
I have a 300 win mag in a Remington 700. It is mag na ported and is as tame as my 220 swift now. I only use it on the occation I am hunting the cramberry bog that runs for nearly a mile between two cedar swamps. Have got a couple good bucks close to 400 yrds out with it.

I get elder moments bad.