The Firearm Blog took a look at this holster made for 1911s with Recover Tactical's CC3G Grip. The grip allows 1911s with no rails to have a rail, but it
increases the width doesn't increase the width, but the dimensions change a little, so a new holster is needed.
http://www.thefirearmblog.com/blog/2015/07/08/review-recover-tactical-cc3h-grip-hc11-holster/
From: The Firearm Blog
Edit: correction from Recover Tactical below.