SUAREZ MARITIME SPRING CUPS
The misconception is that these "maritime/marine" spring cups were designed for the purpose of firing the Glock pistol submerged. While that can be done, it falls under the "don't try this at home kids" category. Actually, these were designed to allow water to drain out of the firing pin channel faster when making the transition from waterborne to land operations, as well as to allow the firing pin to function freely and reliably if any water remains there. Moreover, we have found that with less contact area in the firing pin channel, these cups tends to give a very slightly crisper trigger break.
The original Factory Maritime Spring Cups require credentials few of us have (can't have those pesky civilians shooting near water), but these exact copies are available to anyone.