As anyone swapped out their FCU between 45 ACP and 9mm P320's? I was told they don't, but I did with mine and they worked at least with magazine charges. I'll fire them tomorrow and update the thread.
Originally posted by Hansgruber: Seems like it should work even though the .45 is a larger magazine well size...please post your findings because many would like to know!
The search function will show that this has been covered here many times.
---------------The Answer Is There Is No Answer---------------
I have read accounts from several people who have tried this and reported that the .45 ACP FCU does function with 9mm/.40/357 SIG uppers and the correct magazines.
SIG does not sanction doing this. I believe that using a .45 FCU with smaller calibers defeats the "magazine safety" aspect of the FCU, i.e, the feature that prevents the slide to be removed if a magazine remains in the pistol.
So as it stands. My P320 45 ACP FCU fits into my P320 9mm perfectly and fired without issue. Zero issues with magazines, feeding, etc. However, my P320 9mm FCU will not function in the P320 45 ACP. Bottom line, the larger 45 ACP magazines are blocked into the 9mm FCU.
