Some of my Stanley/Bailey planes, even with the original blades, have tight mouths. Some have been altered, most have not.
Yesterday some time was taken to rehabilitate an old #3. There was a chip at the back of the mouth that was filed away.
Even with a mouth that is a bit wide it can still take fine shavings. It can also take heavy shavings. One of the fatter cuts, I call them zipper cuts because that is what they sound like when being made, measured at 0.021". Save that sucker for when a shim is needed.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)