There are two sizes of guitar bridge pins here. They differ in shank angle (see above illustration). Shanks function to seat or fit into the bridge pin holes drilled onto the guitar bridge and top plate. The taper provides a wedging effect when a bridge pin is driven into a bridge pin hole thus the pin gets "wedged or locked" into position. This effect holds guitar string into position. To get a proper fitting, you should purchase bridge pins with the suitable shank angle. Alternatively you could get your guitar repair tech to modify the bridge pin holes during the next guitar services.
Remove your existing guitar bridge pins and determine the shank angle of your bridge pins.
3º degrees shank bridge pins
The average underskirt diameter is 5.40mm. Generally,
these pins are suitable for for Martin guitars that were
made before 1994, also Larrivee, Blanchard, Garrison,
Goodall, Ryan, Lakewood, McPherson, Santa Cruz and
Taylor guitars.These also work with Collings guitars
made prior to 2002.
5º degrees shank bridge pins
The average underskirt diameter is 5.35mm. For modern
Martin guitars (after 1994) and Gibson guitars.