Earlier quoted context omitted.
While you never know who's armed and who's not, in these cases they're probably just as worried about the destruction of evidence - a polite knock on the door and an 'excuse me, sir, we're the FBI' might give him time to erase or destroy something.
| While you never know who's armed and who's not This may be true, but if the person has no history of violence, isn't wanted for a violent offence, has no registered firearms, and is not known to have any radical anti-government / Michigan Militia-type views, then there is probably no reason for such an armed assault. | in these cases they're probably just as worried | about the destruction of evidence So a group of…
And either way I don't see why you'd not be OK with rifles but would be OK with handguns. Once you're OK with the arresting officers being armed the rest is just a matter of degree.