Use a wood dowel or a brass rod.......tap it out. Do not put anything that that could scratch the inside of your barrel. It will tap out. if you have to put your barrel in a vice, make sure you wrap it securely in a rag or something so again, you do not scratch your barrel
I had the same situation. Saw a set of grips I had to have and they did not have the ambi cut. I used a set that did as a guide and I dremeled them out. They fit perfectly and the gun performs without issue.
That is awesome that you took the time to photograph an install at your facility and then share with the members here.!!.....Nothing sells better than good quality photograph's!!
My wife made it...she sews everything...all the curtains, shower curtains etc........got the material at JoAnn's Fabric's............in Snellville up hwy 124.