The writer in this case made use of Pathos by using the case of his son’s death from a gun accident to evoke emotional aspects of this letter. This is so that the reader will sympathize with the writer on the accident. Also the reader will understand your perspective and be more likely to accept your claims. Being able to evoke sympathy will help the Reader to act on your call to action.
The writer in this case made good use of Logos to convince the reader why he should support the gun control legislation. The writer written many statistics on the problems with owning a gun. The way he wrote it simultaneously make his argument stronger and competing arguments weaker, which let the reader be convinced by the writer.
Lastly for ethos, although the writer may not be a high ranking person or an expert on guns, but he has lost his son through a gun accident, which automatically causes him to be against the freedom of guns. This is why the reader will believe him as he has a reason to have gun control legislation.