By 'float', I am going to presume you mean have a free-floating handguard, and not 'toss it in water and it won't sink'.

Since the 15-22 handguard is attached to the upper receiver at the barrel nut, it's already 'free floating'. You can safely remove the handguard end-cap without any issue. Flexing the handguard does not impact the barrel.

Now, flexing the handguard may impact the front sights...