Custom post types archive redirect

The link to the archive page is saved into WordPress rewrite rules. These rules are used to locate several locations on the front end of your WordPress system. When you change the slug of a Custom Post Type, the normal pages will redirect directly to the new location, but the archive page won’t, this because the rewrite rules aren’t regenerated.

To solve this, go to Settings -> Permalinks and save your permalink structure again, reload your page and the archive page will load correctly.

The rewrite rule in your .htaccess won’t be needed.

Also, never put any rewrite rules in your .htaccess except the ones WordPress writes into it.
If you want to add some rules, do this by using the Rewrite API.