Just a guess...
(Aided by Google...), but considering the gold trigger and hammer − which plating was almost certainly aftermarket − it seems at least possible that the "crown over a C" is s hallmark designating silver plating on the rest of the gun.
"References"
• Silver Forums at 925-1000.com (First "hit" on Google...)
• Online Encyclopedia of Silver Marks, Hallmarks, & Makers' Marks (First answer in thread...)
See the "MC" set of "Unidentified Silverplate Marks", fourth from top on the left. (NOTE: Site images are copy-protected, so I didn't try to repost them here. You have to visit the Encyclopedia website to see them.)
Since the "MC" set includes a "crown over a C", and because it says "Unknown probably USA" right next to it, I thought it worth going to all this trouble to post what is basically a WAG on my part.
Hope it helps. 
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Complete thread:
- Colt 1911 experts, please advise. -
Andrew,
2013-02-22, 12:46
![[*]](themes/default/images/complete_thread.png "Open whole thread")
- Just a guess... -
FOG,
2013-02-23, 02:54
- I had never thought of silver plate.... - Andrew, 2013-02-23, 07:29
- Forgot to mention: I'd advise buying it - FOG, 2013-02-23, 03:11
- Carefull -
JLF,
2013-02-23, 12:37
- JLF's right... -
FOG,
2013-02-23, 15:31
- I never seem to be able to hang onto 1911's anyway. -
Andrew,
2013-02-23, 19:42
- Bully! for the Brown Rifle Days! - FOG, 2013-02-24, 16:35
- I never seem to be able to hang onto 1911's anyway. -
Andrew,
2013-02-23, 19:42
- JLF's right... -
FOG,
2013-02-23, 15:31
- Just a guess... -
FOG,
2013-02-23, 02:54