Here is something good to check. Insert a mag into your 1911 and press the mag release real hard and see if the mag drops free. Sometimes the button side of the mag release has a little to much material and it will contact the mag tube and hold it in the gun.
You may not notice this under normal range use but at a match or in a stressful situation where you are trying to hurry you may apply more pressure and have problems with it. Luckily it's a very easy fix.
Here is the mag release from my CBOB. I circled the problem spot on the release. Looking at it close there is a shiny spot where it has been contacting the mag tube.
You just need to take a little material off that area and break that sharp edge a little bit.
After hitting it with the dremel I rolled a piece of 600 grit around a pencil and polished it up real nice.
Installed it back in the gun and problem solved. Mags now drop free even when I press hard on the release.