just put one of these in an akv. It was the 8" version.
Remove the rear mounting bracket and the front mounting bracket from the rail.
Take the rear mounting bracket and remove the tension screw. Put some thread locker on it. Probably blue but I used red. Stick it in the receiver. It should be loosy Goosy. You need to tighten the tension screw enough to the point where you have to tap it in. It should fit tight. No wiggles. Once it fits solid, leave it in there.
This is a time consuming process.
The front mounting bracket has two tension screws. The two tension screws take up the slack and put tension on the front hand guard retainer of the rifle. Remove them and put some thread locker on them. Put them back in the mounting bracket. Install the front mounting bracket back into the rail system. Now put the handguard on the rifle. Put the front handguard retainer in place and close the cam lever. If it's loose or rattling remove the rail from the rifle. Remove the front mounting bracket from the rail and turn the tension screws out a little. Then reinstall. Keep doing this until it fits rock solid. It's a pain in the ass but it's worth it. Make sure you put thread locker on all of the screws and let it cure. Make sure you don't strip the screws. I should have made video.