JBL, Competition Magnum (Open Muzzle) All Spearguns >>> Spearguns by JBL More details and ordering info. The Competition, Sawed-Off, and Mini-Magnums may be used for both reef and rock fishing and where long range and heavy penetration are important. User input on Competition Magnum (Open Muzzle) by JBL: Be the first to submit input on this product Submit Input: Your Name: Write or Paste Input here: Upload picture:      Review Guidelines