I know the forum says S&W-Smithing but a forum search yielded Colt questions so I assumed it was safe to ask here. Bought a D frame pin for a Colt Detect Special thaqt was missing when I bought it. Original pencil # stocks fit fine due to the shelf on the bottom of both panels that grip frame rests on but when attempting to mount Eagle boot grips they "wiggled for lack of a better term. Problem is pin wont go in in after light tapping with a brass mallet over a drilled out rubber puck. Is there a trick to it? Were the grip pins all different diameters on different frame sizes? Does it need to go from one side of the frame to the other? Thanks in advance.

The small "D" frame Colt's use a stock pin specific to them.
These are smaller then medium "E&I" frame models like the Python.

The frame pins are very often really tight fits.

The pin can go in from either side, but a sort of standard on firearms pins is usually to install from the right side.
This is not always the case and the Colt frame pin isn't side specific.

Options.......

Put the pin end in a drill, run it at medium speed and use wet or dry fine sand cloth over something like a file to SLIGHTLY reduce the diameter so it's easier to install.

Better option is to use a vise as a press to install the pin, which does need to be a tight fit in the frame.
Get a buddy to help hold the gun to prevent slipping and damaging it.
Put a block of some sort with a hole to pass the pin in one side of the vise.
Put brass or copper sheet in the other jaw to protect the pin.
Position the pin into the frame hole with the frame in the vise.
Tighten the vise to press the pin in.

Thanks Dfaris, always try and modify the part not the frame!

Started the pin in, flipped frame over and filled opposite side of pin hole with Ballistol. Soaked 2 days and pin tapped right in.

Ehrrrr ya go.