Wow! I read your Dad's story, and my Dad's story is nearly the same!
Not sure if you were looking for others to share "Dad stories" like yours in this thread, and I'm certainly not trying to hijack it; but I'll share mine with the group as well...
My father served in the Marines during the Korean War. He went in at Inchon, and became one of the
Chosin Few. My father had never finished high school but was, nevertheless, intelligent and had great common sense (two attributes I like to think I inherited from him). He also seemed to have that Irish charm that immediately endeared him to all that he met. Sadly, I did not seem to inherit that trait...

Like your father, mine was a gun enthusiast as well -- to the point where he moonlighted as a gunsmith. Many evenings he sat in our basement, with me at his side to hand him tools, tinkering with someone's pistol or rifle...
At a later stage, he'd given me a Marlin Model 57M that had no stock and a broken firing pin in it -- the latter of which was about as hard to find as a hen's tooth for some reason. Together, we set about finding the replacement part -- which ended up taking several years. My Dad was also fond of doing the finishing work on the stocks (as well as refinishing old furniture) and decided to dress up this run-of-the-mill Marlin with a Circassian walnut stock; a friend of his did some light wood engraving & checkering on the stock and my Dad put the finish on it. Once the firing pin was finally in our hands, the rifle was reassembled and test fired -- successfully, I might add!
My father passed away in June 2016 after a battle with cancer (melanoma). Like you, I carry fond memories of him, but our last hurrah came a week before the 100th running of the Indianapolis 500 race -- which turned out to be three weeks to the day before he died...
I had made arrangements to take him to the track at Indy to participate in a Pace Car reunion that was being held a week prior to the race. A friend of mine was going to have two Corvette Pace Car editions at the reunion (a 1998 and a 2007), and I thought the trip would help to lift my dad's spirits, since he'd always been a big fan of the race. It did -- especially when we got to drive around the track with the rest of the pace cars (my friend let us pilot his '07).
By May of 2016, I had been working back in Waco, TX once again, and flew home to Pittsburgh (commercial flight) for a little more than a long weekend (because we were in the midst of a flight test program) in order to take my Dad to Indianapolis. I had seen him only a month or so before, at Easter; but could see that the cancer was taking a heavy toll on my father. But he was still eager to head to Indy, so we set off. As we sat watching some of the cars doing their qualification laps, I couldn't help but think to myself, "Is this the last thing I'll ever do with my father...?" I drove my father back to Pittsburgh the following day, and the day after that was on a commercial flight back to Texas.
Two and a half weeks later, my brother called me and told me the doctors had only given our Dad days to live. First thing the next morning I was pulling my little
Cherokee out of its hangar, praying that the gimpy battery would give me two good starts (I had to make a fuel stop in Tennessee) so I could get to Pittsburgh before he passed. At about 8 PM that evening, my Dad and I set eyes on each other for the final time; the cancer had progressed to the point where he could no longer speak, and my siblings had had the nursing staff delay his pain medication so he'd be awake and cogent when I finally got to the hospital room. When I came in, one of my sisters told him, "Tim's here!" and he perked up enough to look at me and nod a greeting. I spoke to him briefly before the nurse administered his pain medication, and he slipped off to sleep. He was gone by 8 AM the next morning...
The only solace I could take from it (besides getting there in time to see him before he passed) was that my siblings related to me how, after returning from Indy, our Dad would corner anyone who would listen and tell them about his trip to Indianapolis Motor Speedway -- and how great of a time he'd had...
We all returned to our childhood house in which our Dad had still lived (Mom had passed away in 2014) and decided to honor him by sharing his favorite cookout meal: steak and a baked potato. My brothers and I also decided to lower the flag in the front yard to half-staff -- which could only be done by literally taking the flag pole out of the ground, moving the flag lower on the pole, then returning the pole to its hole. On the first try, my sister captured the event (see attached photo) -- which we all agreed was a fitting tribute to a former Marine...