I use them on my A2. they are fine,
You tap them into place with a drift and a mallet, the recoil holds them in place.
Older versions have screws in the top of each one which marked the action when they screwed them down to lock them onto the action, but they were dropped for that reason plus the fact that recoil holds them.
Obviously you need the rings as well.
It is the front base which gives the security as the ring locks into it. The rear ring is held in place with the securing screws.