I was given a Safariland 014 Open Class Competition Holster that I would like to use with my Performance Center Ported M&P CORE in .40 Smith and Wesson. At first glance, it appears that the part of the holster that grasps the trigger guard is too narrow, and I don't see any means to adjust it. The original owner used the holster with a custom built 1911.

Can one or more of the more experienced users offer any advice?

Thank you for your time.