Only solution i recommend to add a left sided mag release to a right hand only lower. - Cmmg, Inc AR15, Ambi Magazine Catch

I got my aero precision lower on sale but I also wanted to have a left handed mag release. I didn’t want to spend $300+ to buy an Ambi lower. Though there are lots of after market parts you can buy, the issue I ran into a lot was they tend to add extra height/width leading to the mag unintentionally being released when hitting against my body. This 100% exists and functions within your existing mag catch space, no more no less. It also makes it possible to have an existing lower to have ambi mag release with a BAD lever since it doesn’t interfere with the bad lever.