Sure you can.
Figure out what you want to do with your rifle, first. Second, figure out how much money you want to spend. That will guide you towards particular lasers. Most likely, you will need a rail of some sort to mount it on. Anything from a single, plastic rail section that mounts to your hanguard to a free float handguard, front sight or barrel mount or anything in between, will do it.
There are a few lasers that are configured to ride on top of the barrel, behind the sight, but many people don't put the laser there anyway. The way the light activates will guide you to where it needs to sit on the rifle. Also, if you have a flashlight, fore grip or other whiz-bang stuff will guide or limit your placement.
If you are talking visible lasers, nothing is going to work out to 100 yards in direct sunlight. If you get a quality unit, they will work well on cloudy days, evening and in darkness, but not direct sunlight.
Figure out what you want to accomplish, look around a lot (because there are a lot of configurations to choose from), and bust out the check book.