You will need a gunsmith to find out.
'ACP' means Automatic Colt Pistol. A 1911, for example, would chamber a .45 ACP cartridge.
45 ACP
Any manual for a Colt 1911 will do.
Answer The Colt .45 caliber automatic pistol was accepted as the standard side arm of the US Army and became identified as the Model 1911 Pistol. The bullet developed for use in this new design of automatic pistol was called the .45 ACP or the .45 Automatic Colt Pistol cartridge. It stands for "Automatic Colt Pistol" because it was adopted for the Colt 1911 only by the US army.You get many variants the most prolific being the .45 GAP for glock handguns.It's patented I believe.
Colt Firearms ((named for its founder, Samuel Colt) was one of the firms that made the US Military Pistol, Cal .45 ACP, Model 1911. It was adopted by the US Government in the year 1911.
Proofhouse.com has Colt serial numbers you can look up
1970
about 1913 value depends on condition
about 1978
Manufactured in 1978.
check pistol aagain. serial number appears to high for the 1911 military
Impossible to answer without hands on examination.