Hi John,
Welcome to the collectables section of the BBS.
The batch numbers can't be used to date a pistol unfortunately. The 4 was dropped in 1958 rather that 1953.
If you start another thread and post pictures of your Senior, the anoraks on here may be able to help date it for you but generally speaking, a Senior can only be narrowed down to a period of several years, such as 1946 - 1949 or 1950 to 1958, etc.
Kind regards,
John
Currently looking for Baikal Makarov pistols with the following prefixes to the serial number: 98, T01, T09, T21, T22
Prefer boxed or cased but will consider loose examples too.