Lol, personally i think the bullet size can be bigger .
For folks who aren't accustom to difficult games, perhaps you can subtlety lower the difficulty a bit without even letting the player know it too. For example after like the 5th retry or so (there will be plenty of this), and also depending on the level, you can slow down some of the moving obstacles, slow down the chasing enemies, increase drag slightly, gravitate bullets towards the target.....etc. But do it all behind the scenes so that a player isn't "forever stuck" on a certain level and will be more enticed to continue playing. This technique was actually done in Resident Evil 4 - not a lot folks know this though .
The problem with this method is it ruins the flow and timing. If an enemy/obstacle behaves a certain way or moves a specific speed, you expect them to always move in that way, which is fundamental to how you would react.
In a game like this, where timing is everything, if you start adjusting the seed of objects after the player dies, the player will have to adjust their tactics. That might become frustrating after repeated attempts when objects don't move like they once did and you have to relearn the level all over again.