IMHO, either removal of the bolt or installation of a chamber plug (open bolt indicator) adequately demonstrates that the weapon is safe.
The chamber plug has some advantages. It is highly visible; it's applicable for rifles whose bolts are not easily removable (e.g. BSA Martinis); and if you use it at your club for all shooting disciplines, shooters only have to be trained in one safety procedure.
For several years, we have used chamber plugs for our Schuetzen, smallbore, and benchrest matches. We are completely satisfied with them.
We use ones from the CMP. They are plastic, bright yellow, and are "one size fits all" from .22 up through at least .30 caliber. The CMP calls them Open Bolt Indicators (P/N 244) and sells them for $3.99 per dozen. CHEAP INSURANCE!!!!. We sell them for $1.50. That makes a small profit for the club, makes them expensive enough that shooters don't want to lose them, and are still reasonably priced.
If you want them, buy early. The CMP is backordered several months.
While we're on the subject of safety, our club sells EAR disposable ear plugs at the matches. We don't require them, but we do make sure that they are available. If you shoot without hearing protection, it's not because it isn't available.