GunVault have introduced a new gun lock for Winchester, Remington and Mossberg pump action shotguns called BreechVault. As the name suggests, it locks into the breech. The magazine can still hold ammunition so chambering a round simply requires the lock to be removed and action pumped. The lock is made from \glass nylon so it will not damage the gun.
Locks are often frowned upon by self defense experts, but some people cannot legally leave their guns unlocked, or are simply unwilling or unable to do so for whatever reason.
The MSRP is $19.95.