Converted your BK1S or BK2S to Talon Magazines? Here is the mag catch you will need. You will need to file down a small slot from the inside of your mag catch. You can slide the part into this slot on an angle and it should fit perfectly. The changes are not visible from the outside, and you can revert to the original catch if desired.

You will need a small M2 screw to fasten parts together. The screw head will be recessed and you can affix the ambi-release paddle with a piece of filament as a pin.

Print the catch with 3-4 walls for rigidity. Recommend no supports used except for the ambi mag paddle.