I took a closer look at the spring and found out that it makes a lot of noise when slide is closing, as if it were binding on something. Weird. Could be that the spring's gone weak and bends in funny ways when compressing (?). Anyways I'll try and see if a new spring will help. I saw Wilson recommend #18.5 for stock 1911 w/full loads (www.m1911.org), is it really too heavy? I seem to be getting mixed opinions here!