Senriku

Senriku is the rifle used by Van Augur. The name of this weapon comes from One Piece Yellow: Grand Elements.

Design
Senriku has an extra-long barrel with a widely-flared muzzle, similar to a blunderbuss but highly exaggerated. The end would normally render the cross-hairs placed just behind it useless, though that does not seem to be the case.

Abilities
Senriku is capable of shooting down targets from an extremely long range. With it, Augur can hit a seagull flying so far away from Jaya, his location, that the island can't be seen from the seagull's position. Also, Auger is capable of firing rapidly, as demonstrated with Portgas D. Ace as the target.

In the ninth movie, Van Augur was seen firing explosive rounds with this weapon during the attack on Drum Island.