Re: Sig P220 reassembly problem
Its probably the locking block being too high. It may be because the trigger pin is flipped with the notches facing upwards when they should be downwards. the locking block can be inserted with them upwards but with difficulty inserting the lock lever and having the block not fully seated.
When you duracoated the gun did you duracoat the locking block? remove it if you did. It will cause the barrel to stick.
Only cowards shoot with their eyes closed....