Here's a thought ... rather than spending a lot of time making inaccurate ammo , how'bout selling that pile of 7.62x54r surplus ammo and using the proceeds to buy some proper bullets for your Enfield reloading?Just sold my 7.62 x 54R. Got whole lot of surplus ammo. Thought of using bullets and powder in my .303 longbranch and that undersized bullets would let gas through and dammage to the bore.
"Much faster than conventional reloading" ... that makes it sound like you are replacing the bullets in .303 cartridges with the 7.62x54r bullets.... Time consuming ? Much faster than conventional reloading after you find a quick way of pulling bullets out (made myself a tool for it) ...
Powder coating, if done properly, shouldn't add to the diameter as the bullet gets sized after the coating is applied.A powder coating could add some to the diameter.
CC