“miss at” vs “miss by”

Question

I want to know the meanings of the following sentences:

1. John missed at 50 yards.
2. John missed by 50 yards.

Does #1 mean that John missed (a mark? or what?) at the place 50 yards in front of something (a mark?)?

What does #2 mean?

According to one explanation I read somewhere, #2 means “how far I am to the side of something”. But I don’t know what they mean by that.

Does #2 mean that John missed something at the place 50 yards away from something?

Answer 1

Neither of your sentences is grammatical in English. Do not precede the measurement with the indefinite article. Those should instead be:

1. John missed at 50 yards.
2. John missed by 50 yards.

Now that they have been corrected, the first means that he missed the target which was fifty yards away from John himself, while the second means that wherever he actually hit was itself fifty yards away from the target.