A foolproof method nearly guaranteed to work for the stubbornest. It will require an investment. One that a monetary value cannot be placed on if your folks ever have to actually use their guns.
Send them to defensive pistol classes.
snipped....
...I don't try to tell my dad what to do... He's a big boy and can make his own decisions... After all, he had the strength and wisdom to raise me, right? If we're discussing the matter - well, I may make my opinion known. But at the end of the day IT'S HIS LIFE. And as for my mom - well she chose to marry HIM not me...
Opinions are freely given - what people do with them is their choice. My wish as their son (for them to see things the way I do) does NOT trump their free will - at least that's my opinion. I fully capable of screwing things up well enough myself! I don't need to add their decisions to the list and second guess them and sweat that as well.
Also - let's put it in perspective - it's a choice of an LCP vs. a Glock or something. It's not like he's choosing whether or not to go play on the freeway or something immediately threatening. It's a _preference_.
Better to have a mouse gun and carry it all the time than to have a larger gun and leave it at home or in the car.
You can't change his mind just like he can't change yours. It is all about choice and what works for you.
I always find it funny, personally, when people try to say that anything less than a certain caliber is just going to make a perp mad should you need to shoot. Carry what is comfortable and accurate for you to shoot. It does little good to carry a 9mm, .40 or even a .45 if you can't place shots where you want at 10 yards.
You should shoot my 21a sometime. Ammo is spendy but I put all 7 rounds in a big slam bottle at 10 yards nearly every time I get it out. I'm amazed at its accuracy and don't know whether to attribute it to the fact that it's a Beretta or the fact that it's centerfire?To be fair, a .25 auto would probably just make the bad guy mad. There may be some decent shooters out there in .25 but the 3 that I've shot were nothing but junk. It was hard enough to keep on paper at 10 yards for multiple shots(if you could get multiple shots without having some sort of malfunction).