Awesome game. Found the best strat was to have side-by-side bullets and always prioritise miracle rings!
Beat the game three times and each run had:
Adds a chamber to the gun
The first bullet after a spin has a +20% chance of miracle
Add 20% Miracle
Add 20% chance of miracle occurring when you don't have any item
This gave me 5/6 chance of success on most rituals (when down to one bullet), and that 1/6 scenario had a 60% chance of miracle (reset on every spin).
Even first ritual, pump two bullets in. When you get to one bullet, spin the chamber. Resets each shot to 5/6 chance of success. Later rituals, ALWAYS grab the restore health (necklace), skip the next chamber (cog), grant 100% miracle (book), and optionally select the reveal whether chamber has a bullet (monacle).
When you shoot and find the first bullet, skip the next bullet in the chamber with the cog and then click freely four times. When only one bullet is in the chamber, go back to spinning after each shot.
Quick money grab (better if 50$ discount ring is obtained): Buy the 5 gold per bullet upgrade and the tool to open the gun (22 gold together or 11 gold with discount). Put all the bullets in the chamber, use the item to get 30 gold, and then re-open the chamber and remove additional bullets. Alternative, keep the bullet upgrade item until the end of a run, shoot until you're hit (requires extra health), then pump the bullets in, and use the item before finishing the ritual.
Last ritual is tricky, but you want to ensure you have an additional slot in the chamber, and go for a BULLET-BULLET-BULLET-EMPTY-BULLET-EMPTY-BULLET configuration. This ensures you will have two bullet attempts to either miracle or use an item until reaching an empty, and odds only increase as shots come out.