Best way to level up crafted shotguns?

[polar hedge]

I am at Shiro Chi and I keep running out of special even with special ammo finder slotted. Its been taking a bit of time and I was wondering if there were any better methods for shotguns?

[haughty linden]

Use raid banners

Also do double special + heavy loadout (machine gun etc) so kills with heavy can only drop special ammo