I'm building up a spare bolt and the plug I have for it has the knurled OD rather than the wrench flats which were on my original bolt's plug. The pins which I have for it slide into the hole in the original plug just fine but although they will start in the hole in the new knurled plug they will not go all the way through. There is something in the middle of the hole which is stopping them. I think it may be a spring loaded detent but I'm only guessing on that.
Has there been a change in the pin? Or do I just drive it home with a punch?