This albeit, might be overkill, but why not just use multiple raycasts? Raycasts are pretty cheap as long as its not crazy range (you can just make the range really short to extend to the bullet size) and boom bam done, you got a working large bullet projetcile that is moving fast while hits accurately (I think).
You can try utilizing this module:
Or just have raycasts pointing in the lookvector of the bullet and have the range be shortened to the same width of the bullet.