I have a Martini Cadet with a pristine .316 groove diameter, which some goofball ran a .32-20 chamber reamer into undoubtedly to circumvent needing to make/find .310 Cadet ammo. Normal soft .312-.313 diameter 100 grain pistol bullets bump up sufficiently upon discharge to seal the bore well enough to give very good accuracy and no leading.

"You can lead a man to logic, but you cannot make him think." Joe Harz
"Always certain, often right." Keith McCafferty