I am surprised to not see much mention of the Advantage Arms Conversion. I have the standard conversion hosted more or less permanently on my Kimber Eclipse with a 18# main spring and a C&S ignition package. It is very accurate, fits perfectly in my 1911 holster, is totally reliable with CCI Mini-Mags, locks back just like my 45 acp 1911's, and the mags are $25 each. I did send it to Novak for a FO front sight. Mine has just about 10,000 rounds through it and other than cleaning it every 5-600 I have changed the recoil spring once. Having an AL slide the set up is lighter than my 45 acp 1911's but I have gotten to hardly notice the difference.