Problem replacing pinned front sight

[gunsrfun1]

I'm attempting to remove the solid pin that holds in the front sight on my model 640 so I can replace it with a fiber optic. I did it years ago on my 686, but this one is proving stubborn.
I seem to recall that I used a 1/16 punch to remove the pin, but I'm not sure. The hole that needed to be drilled in the replacement sight was a #55 drill bit (.054); that I do remember. And it worked out fine.
So ... would you recommend that I try a 1/32 punch if I can find one? Or will the 1/16 punch suffice if I can get the pin started? I have tried using the blunt end of the #55 but it eventually broke; the drill bit isn't that robust.
It does appear that the 1/16 might just fit through the hole in the sight base, but I am not entirely positive, since the pin takes up almost the entire hole. It seems like it might work, But I don't just want to wail on it.
Also putting some penetrating oil on the hole, to help out.
I've also read that a #5 cup pin punch (.050) might do the trick.
Any ideas?
Thanks

 

[mikerjf]

Will be watching, since I haven't done this yet.

But I've heard tell that the stock pin is #54 drill size, which is about .055".

Some people go up to a 1/16" bit and roll pin, which would be about .0625".

So you can see why the 1/16 punch isn't working on the stock pin.

 

[gunsrfun1]

Well, so far, no joy. I made a .053 punch out of a drill bit, and cannot get the pin to budge.
I may have to order a .050 cup pin punch from Brownell's. It'll end up costing me ~$25, but I don't want to damage the gun.
If anyone has any ideas, I'm all ears. Thanks.
My 686 was so easy ....

 

[Toolguy]

You will have to use a punch smaller than .055. There are short "starter" punches to get the pin moving, then you can use a normal length one to get it all the way out. The .050 cup pin punch would be an excellent choice.

 

[gunsrfun1]

Great idea, I ordered a .050 cupped pin punch from Brownell's and it worked. Pin came out fine.
Thanks