Ok, If I use a proxy, the home office (they monitor net use) will not see AR15.com on their printouts?

I don't know, used the anonymizer to hit a few sites and they are still showing in my history bar, I know the home office monitors the history bar.

Assuming you are talking about using a proxy that is outside your company intranet. If you do that all traffic looks like its coming from the proxy server IP address instead of from where it is really coming from.  Seeing you go to one IP all day will set off warning bells and they may look at content or deny access to that proxy site.  If they monitor content then they will see the ar15.com information.

If they monitor the history bar why not clear it when you are done?

Used to support internal proxy servers for the place I work. Would get called to look through the logs and bust people for surfing places they weren't, porn to hotmail anything against policy. Those people got fired.  If they watch it that close there is a good chance you will get busted. Is it worth the repurcussions?