3- the thumb safety, grip safety, and half-cock safety.
I remember back in the early 70's at MP school at Ft. Gordon the instructor also mentioned that if you fall forward or in some way compress or put pressure on the barrel it would not fire. this would be a 4th safety. I also can't remember for sure but it seems that if the magazine is not locked in, it wont fire either. Not sure though, it's been a long time.
Colt 1911-A1
With the serial number that you provided,your Remington Rand made 1911-A1 was made in the year 1945.
About $500
Your 1911 serial number indicates your 1911 was made by Colt in 1918.
1905, 1911, 1911 A1 were all predecessors.
your 1911 was made in 1912 by Colt or Remington
Six to seven hundred dollars.
your 1911 serial number indicates your 1911 was made by Colt in 1914
The Colt 1911 A1 is rated at 395 FPS (Feet Per Second)
Your 1911 was made by Colt in 1918.
The A1 wasn't issued till after 1924 I believe..
1968