Colt mags were modified Uzi mags, just a new mag catch slot cut in them. So they had both cuts and could work in 9mm ARs and Uzis.
There are now dedicated mags made for 9mm ARs that only have the Colt AR mag catch slot cut in them. These types would require an Uzi mag catch slot cut into them to work in an Uzi. However, some do not have the little ears that function as overtravel stops for an Uzi that hit the bottom of the Uzi magwell. I do not know how important those are, but I am sure you can get some Colt style AR mags to work in an Uzi. There are some Colt style mags with a Last Round Bolt Hold Open (LRBHO) device added to the follower and a mag body that isn't just rectangular and has an extra bit outward on the rear that I believe would prevent their use in an Uzi.
"Colt" mag slots are near the top of the magazine body, on the rear corners. The Uzi mag slot is much smaller, on the left side of the mag. The Uzi overtravel ears are on both sides.
Link a picture of your mag. There have been a lot of variations.
