Ergonomics on the AR are best when they allow the shooter to keep his dominant hand on the pistol grip and the secondary hand free for support and assisting in malfunctions.
The Battery Assist Device from MAGPUL is a huge asset to add to your AR15 rifle. This lever helps you get your rifle into battery. The installation is very quick and does not require you to remove the original bolt release latch. Nor does it require you to change any of the pins in the latch. Instead you simply add the BAD to the original bolt release latch face.
The BAD lever allows you to release and lock the bolt with your index finger while operating the rifle so that you are operating with minimal efforts. The BAD lever allows you to use the same index finger that is used for the magazine release.
For frequent shooters, muscle memory will be to tap the bolt release latch with your palm when the bolt is locked to the rear but now you have the option to release with your trigger finger. Another option you have when you’re using a standard capacity magazine, is that you can quickly place your thumb on the BAD lever and release the bolt.
You have several more options in which to manipulate the BAD lever. The best way to see what works best for you is to try and operate the lever with practice. You can be confident that the lever will stay in place and that the lever will give you more ease when shooting rapidly.
The lever also allows you to keep your rifle in the shoulder pocket that is critical to fast target acquisition. No one wants to have to raise the rifle and lose their placement if they can avoid it.
Keep training as always and stay vigilant. The more you train with magazine reloads the faster you will be when the time is critical.