Many years ago I opened up the chamber on a Savage .22/.410 to take .22 mag. ammo and I never had any problems at all with it. Performance was fine. No sign of high pressure. Lapua Midas L and Lapua Midas M are different diameter .22 match ammo as some rifles like slightly larger and some like slightly smaller. .002" in a .22 rimfire isn't enough to fret about. My opinion only, your's may differ.