A 9mm FMJ 'might' have enough momentum, if the chain was sufficiently secured.

Lest we forget, the momentum of the bullet is only part of the problem...

There is a reason why, even thought Glock sells parts to make their firearms (9mm only) fully operational under water, they recommend against it. The concussion could kill you. "The shock/pressure waves in water can really damage internal organs" - GlockFAQ

http://www.glockfaq.com/content.aspx...Glock_Info#h2o