To me this makes sense, and I really hope it makes sense to my GM's also. I put this to them so I will end up going off of what every they say but I want to get a feel for this.

So this is my question as an Outlaw Tech with slug throwers. Using Tinkerer, I don't modify my weapons, but my ammo, making them armor piercing so they would gain Pierce 1 or 2. Considering Slug thrower ammo is physical, and I bought extra ammo, this makes completely sense to me but I am hoping GM's won't see this as a sneak around to use cheaper weapons.

Do you mean 'jury rigged' because Tinkerer just adds hardpoints to items.

As a GM, I'd allow Pierce 1 for slugthrower ammo, but only specific to that size, rifle vs pistol ammo. Maybe even give Rifle Pierce 2

Whoops. Completely correct. I meant Jury Rigged.

Rifle vs pistol makes sense.

Surely Jury Rigged is better as is?

With Pierce you can suffer over penetration and the extra Advantage means you Crit more often.

(EDIT: With what gun, Richard? Must think before posting...)

(That said +1 damage vs. pierce 1 - difference is negligible.)