breach / breech
A break in a wall, a law, or a duty versus the rear of a gun or of the body.
A breach is a gap or a violation: a breach in the wall, a breach of trust. Breech is the rear of a gun’s barrel, or the buttocks. In a breech birth, the buttocks or feet come first.
Examples
Use The tenant’s unpaid rent was a breach of the lease.
Use The armorer cleaned the breech of each rifle before inspection.
Avoid The tenant’s unpaid rent was a breech of the lease. (Change breech to breach.)