Bolt actions aren't effected, just semis and kits from fulls that you could build a semi from.
That's not what the letter says:
IF YOU SUBMIT A NEW APPLICATION TO IMPORT FRAMES, RECEIVERS AND BARRELS ON OR AFTER THE DATE OF THIS LETTER, AND THE PERMIT IS FOR NONSPORTING FIREARMS, SURPLUS MILITARY FIREARMS, OR NATIONAL FIREARMS ACT FIREARMS, ATF WILL DENY YOUR APPLICATION
A Mosin Nagant is a Surplus Military Firearm, so is a Mause, SMLE, etc. (There might be a curio and relic exception however)