This is a common question that comes up, since it looks like both perks are similar, and perhaps that Double Barrel is preferable as it leads to Triple Barrel
However, Multishot is generally preferred because
- Multishot affects all your shots - i.e. Forward shot and Spreading shots - while Double/Triple Barrel only improve your forward shots
- Multishot only slightly reduces power of your shots (10% of the Weapon-specific Base Damage) whereas Double/Triple reduces it by much more (30% and 40% respectively)
These reductions don’t affect your gear damage, and you will often have other attack bonuses at play, so to see the real impact, try it for your load out using the Damage Simulator
There are a few other things to bear in mind
- Muiltishot slight slows down your shooting rate, however your overall dps will still increase because of the extra shot
- The power reduction of Multishot affects all perks that cause damage relative to shot damage (Shrapnel as well as Prospero’s Magic Bullets but again your overall dps will still increase
- Double / Triple barrel doesn’t double/triple your Sidewinders (stays at 2 or 4 depending on your perks), whereas Multishot will double them
- With multishot, the shots go on the same trajectory whereas with Double / Triple barrel they stack vertically, so when you are shooting at the edge of a cliff you might find some barrels just hitting the edge, but this is a edge-case (pun intended)