“Force SSL” forces your browser to redirect http://example.com to https://example.com, it doesn’t “force” SSL into the connection. As long as you’re connecting through HTTPS, the traffic is encrypted.

If your browser redirects you from http to https after you turn off Force SSL, there could be two things going on, both related to caching:

1. You turned on HSTS previously and that’s still cached in your browser.
2. The http->https redirect is still cached.

You can check both of these by clearing your browser cache for example.com (or in general).