I have the 3400 Amphibs., so was interested in your post. I first looked at my Aerocet Maintenance Manual (which might not be up to date) and it is unhelpful as it doesn't mention clips or pins in the Oleo Removal section. It simply says: "Item 3: remove the oleo by pulling shear pins."
However, I did trawl through the Aerocet website recently and found a Service Letter (SL08-35A-45065 Shear Bolt) dated 26th September 2014 which replaces these pins with shear bolts and castellated nuts, which should solve the problem once and for all.
It certainly beats lying on wet grass or tarmac in the course of every Pre-Flight Check!!