This is an inexpensive product to increase the capacity of your Glock 43.
https://www.brownells.com/magazines/handgun-magazines/magazine-parts/magazine-extension/magazine-extension-for-glock-43-prod85739.aspx?avs%7cMake%7e%7eModel_1=Glock__43&avs%7cManufacturer_1=tangodown
Wade