It's a novelty mostly, but a fun and strong one that takes advantage of several mechanical interactions.
The short version is you can use a final word 50cal in hand to easily top off both bullet storm and onslaught stacks and use that ~400% damage boost intended for ranged and instead use it as a buff for pain train(perk) melee blender.
The long version is perks, legendary effects, and unique weapon effects that apply to the weapon in hand largely apply to pain train attacks.
Holding a final word you can splatter enemies with pain train and they will add to your bullet storm stack and bullet storm also applies to paintrain. The furious 5% and guerilla 5% damage for each stack of onslaught also apply to pain train.
You can sprint at an enemy while locking on in vats. This will send you into a very tight and dizzy spiral around the target. You are close enough though that you'll continually make pain train attacks without consuming more AP than it takes to sprint. These attacks will charge your crit meter and even crit once filled.
that's it. Take 3/4 of the major damage sources and apply it to both ranged and melee.
if you take Paintrain+iron fist, onslaught perks, and bullet storm perks that's the bones. Get a final word and a set of choochoo Tesla bracer power armor and you are good to go. Use final word to charge your Paintrain, then use your Paintrain attacks to stretch your bullet storm reload loss, and charge onslaught stacks before blending a boss.
There are some very strange mechanics if anyone wants to play it.
* Paintrain alone wount take onslaught stacks above 9, just shoot them till you reach 21 stacks then go back to sprinting and they wount decay.
* Paintrain doesn't degrade weapons or armor. Enemies drop ammo for the weapon in hand. Very resource positive. Soloed aan infestation and the durability of my stuff didn't visually change.
* Gunslinger master will NOT remove stacks when paintraining a target. Meaning if you are heading into a boss fight slot master and your stacks wount diminish and it's an extra 100% damage boost.
* Paintrain does absolutely ZERO limb damage. That's okay because I had to abandon the limb damage stuff anyway.
* Conductors is nice because it appears well to both ranged and melee but polished also works well with Paintrain taking a lot of the durability loss.
