The parkerized finish on the bolt and most of the small parts and the small bow guard leads me to believe the rifle was rebuilt. The barrel appears to be the correct date for that s/n range and is probably original. The stock may have been changed at the rebuild or subsequently. Usually a depot or arsenal marked the stock. The "K" in the cutoff notch is the mark of the manufacturer, Keystone.
Weaver made the 330 in a number of variations. The principal variations had to do with the W&E adjustment knobs. The 330C, later militarized as the M73B1 had knurled knobs with click stops. The 330S (silent) which is what you have got used a screwdriver adjustment. There is no evidence that the 330S was used on the A4 although some appear to have been used on optical intruments such as boresighting apparatus associated with firecontrol radars.
Glad the pics worked out. If you scroll to the bottom of the reply page you will find an option to link directly to photobucket. Using photobucket will make posting larger files (pictures) much easier.
Regards,
Jim