Without a sn, there is no way to answer.
Either 38 S&W, 38 Special, 38/200
Any good reloading manual will get you started on assembling 38 special ammunition.
Impossible to answer without the serial number.
made about 1968
Official Police ser numbers started at 513216 in 1927. I believe you have a Police Positive Special from 1921. It was chambered in .32 Colt, .32 New Police, .38 New Police and .38 S&W, .32-20 and .38 Special.
@ 1970
50
100-300
Proofhouse.com has sn tables.
Early to mid 80s
Impossible to answer without the serial number.
late 1800's to early 1900's