If looking at jp, shooters connection has them in stock and cheaper.
http://www.shootersconnectionstore.com/JP-GMR-13-9mm-Rapid-Configeration-Handguard-P4425.aspx
For me a 5.11 style vest is the fastest and most consistent. However, polo shirts or unbuttoned shirts are near as fast, but on a windy day a light unbuttoned shirt can put up quite the fight when trying to clear it.
Shooters connection has gmr-13 in stock. But eventhough you are a glock shooter pcc will likely have its own big stick glock mags with large basepads that will never be used in the handguns!
Using the idpa classifier as a baseline I've run the same times with stock internal glocks as I have with prepped ESP glocks. As a result I leave my carry guns' internals stock.
Taran Tactical makes a good connector and spring kit. The way of the gun package works well for its cheap price point. Also, if gen 4 gun you can use a gen 3 trigger bar.
I have found that red works the best for front sights. I have used blue but it eventually comes loose and nothing is worse than loosing a front sight in the middle of a stage!
Thanks for the post as it doesn't make me feel so OCD about confirming all of my magazines are full when I am called as the shooter in the hole, and once again before walking up to start position.