What you have is an Ithaca frame with a Colt slide.

 

Thanks for the help. When I looked up the serial number on colts website it said 1911 a1 manufactured in 1943. Would the Ithaca serial number show up on Colts Serial Number look up?

 

Look up the 1911 1911a1 serial numbers by manufacturer on proofhouse.com.. breaks them down by blocks assigned to manufacturers. The FJA inspector mark on the side of your frame narrowed it down to Ithaca or Remington Rand. Serial number is in one of the blocks assigned to Ithaca.

 

Look up the 1911 1911a1 serial numbers by manufacturer on proofhouse.com.. breaks them down by blocks assigned to manufacturers. The FJA inspector mark on the side of your frame narrowed it down to Ithaca or Remington Rand. Serial number is in one of the blocks assigned to Ithaca.
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The 1911/1911a1 serial numbers are part of the Colt listings on proofhouse

 

Thanks! Were the slides and the frames mixed in original production blocks or do you think this is an switch by someone after WW2?

 

Looking at the pictures closer, your slide looks like a commercial Colt slide that just got stuck on an Ithaca frame. The Colt military slides are marked like this one.

 

The slide appears to be a post WW2 commercial slide. May have been post WW2 replacement slide, purchased by the military for post WW2 rebuilds. As noted, Ithaca receiver.

 

your 1911a1 is a 1944 Ithaca ( per Clawson ) with a commercial colt slide . does the barrel have any markings ?
right now it's a 1911a1 mix-master post war or possibly a arsenal rebuild , any other stampings on either sides of frame ?

 

These are the only other 2 markings I could find. Thanks again for the help!

 

Nice 1911A1 even if it is a mix-master.

 

The slide appears to be a Korean War-era replacement slide supplied by Colt. Their markings were the same as commercial Government Models of the same time period, but the flats were left unpolished and typically have horizontal grinding marks. A commercial slide would of course have originally been polished on the flats and remain as smooth as a baby's bottom even after Parkerizing.

 

1960s Colt replacement slide - taken from commercial production and finished.

 

The plain block COLT was in use from 1949-55. After that Colt switched to an italic COLT in the slide rollmark.

 

As noted above post war mix master