rrussell, I have owned and carried Colts for many years, carried them in mlitary and LE and am a LE Colt armorer. The dent has nothing to do with magazines, the case is hitting the ejection port on it's way out. This happens with Series '70 and earlier commercial Colts, military 1911s, 1911A1s, etc, and any others, that don't have the lowered ejection ports we're all so used to now days. If you're not a reloader,it means nothing, if you are a reloader, the case dent will be ironed out during the reloading process. Even the newer guns, with lowered and/or flaired ejection ports, may occasionally dent a case. If the gun functions normally otherwise, nothing is wrong with your gun.
Yes, you can start adjusting the extractor, change or reshape the ejector, etc. to prevent this. If you do, you may find that the brass will be ejected in more of an upward and backward path, possibly into your face on occasion, that extraction and/or ejection may become unreliable, etc....
Last edited by rock185; 02-18-2013 at 08:12 AM.