I know I'll probably catch some flak for doing it... but I had the same problem with the firing pin retaining pin in my new Armalite's bolt carrier. I got fed up with having to "lightly" hammer it in with a mallet every time I'd reassemble. So, I decided to do something about it. I took a sharpening stone and ever so slightly put a taper on the outside edge of each of the two "tines". I found that it goes in a little easier, yet it still retains the ability to hold in the hole. I do still have to use the mallet, but now I don't have to hit it as hard and it goes in alot easier. BTW, just before I started taking some of the material off, I noticed that from all of the hard hammering I'd done, some of the metal on the pin had been "peeled" back - creating an even tighter fit in the carrier hole. It almost looked like a little step just above the end of one of the tines. Now I don't have any problems (unless the pin starts walking out from what I've done????). Either way, I've decided to order a couple of spare pins .... just in case
hsld.