love it

love it

like i realy love it

Feels a little overpowered to me.  I'd probably be ok with the whole thing if you just changed the middle:

• Your bullets now penetrate when you hit an enemy with a firearm attack. The next creature in line with you target (within 30 feet) must make a Dexterity saving throw based on a DC of 8 + DEX + your proficiency modifier. On a failed saving throw the second target takes damage equal to half of the first.  On a success they take no damage.

I think doing this mitigates some of the over-poweredness, and balances it to within 5E standards.  I think a DEX saving throw makes more sense than you rolling an attack.  You already attacked, and it's their job to dodge.  Also, you've already penetrated a target, and thus your bullet would have slowed down a bit.  So I think half damage makes more sense than full damage.

This still leaves the feat powerful, but not overly powerful.

What Viper said.

Gunslinger already has Piercing Shot. Maybe instead you could allocate a certain number of additional grit points specifically for that? Otherwise giving that on every shot feels WAY too op

I agree with Viper718.

The inclusion of a Dex saving throw and the reduced damage is more appropriate. The kinetic energy remaining in the projectile would certainly be diminished after the first penetration. And the inclusion of the bonus attack action seems OP. Perhaps, instead, the bonus action could be an option to reload.

Nice idea for the feat! I shall propose it (modified) to one of my group members.

Spell check: You -> Your

Can the Artillerist Artificer have this?